Letter Islands

                            Solution in C :

In   C++  :









#undef NDEBUG
#ifdef ssu1

#endif

#include <algorithm>
#include <functional>
#include <numeric>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <cassert>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <bitset>
#include <sstream>

using namespace std;

#define fore(i, l, r) for(int i = int(l); i < int(r); ++i)
#define forn(i, n) fore(i, 0, n)
#define fori(i, l, r) fore(i, l, (r) + 1)
#define sz(v) int((v).size())
#define all(v) (v).begin(), (v).end()
#define pb push_back
#define mp make_pair
#define X first
#define Y second

template<typename T> inline T abs(T a)
{ return ((a < 0) ? -a : a); }
template<typename T> inline T sqr(T a)
{ return a * a; }

typedef long long li;
typedef long double ld;
typedef pair<int, int> pt;

const int NMAX = 110000;

struct node{
int l, r, par, link;
map<char, int> next;

node(){
l = r = par = link = -1;
}

node(int _l, int _r, 
int _par) : l(_l), r(_r), par(_par){
link = -1;
}
};

struct tpos{
int V, L;
tpos(int _V, int _L) : V(_V), L(_L) {} 
};


char s[NMAX];
node t[2 * NMAX + 1];
int szt, szs;

int leng(int v){
return t[v].r - t[v].l;
}

int add_edge_to_parent(int l, int r, int parent){
int nidx = szt++;
t[nidx] = node(l, r, parent);
return (t[parent].next[s[l]] = nidx);
}

int split_edge(tpos pos){
int v = pos.V, up = pos.L, down = leng(v) - up;

if(up == 0) return v;
if(down == 0) return t[v].par;

int mid = add_edge_to_parent(t[v].l, 
t[v].l + down, t[v].par);
t[v].l += down, t[v].par = mid;
t[mid].next[s[t[v].l]] = v;
return mid;
}

tpos read_char(tpos pos, char c){
int v = pos.V, up = pos.L;
if(up > 0)
return s[t[v].r - up] == c ? 
tpos(v, up - 1) : tpos(-1, -1);
else{
int nextv = t[v].next.count(c) ?
 t[v].next[c] : -1;
return nextv != -1 ? 
tpos(nextv, leng(nextv) - 1) : tpos(-1, -1);
}
}

tpos fast_go_down(int v, int l, int r){
if(l == r) return tpos(v, 0);
while(true){
v = t[v].next[s[l]];
if(leng(v) >= r - l)
return tpos(v, leng(v) - r + l);
l += leng(v);
}
throw;
}

int link(int v){
if(t[v].link == -1)
t[v].link = split_edge(
    fast_go_down(link(t[v].par), 
    t[v].l + int(t[v].par == 0), t[v].r));
return t[v].link;
}

tpos add_char_to_tree(tpos pos, int i){
while(true){
tpos npos = read_char(pos, s[i]);
if(npos.V != -1) return npos;

int mid = split_edge(pos);

add_edge_to_parent(i, szs, mid);

pos = tpos(link(mid), 0);

if(mid == 0)
return pos;
}
throw;
}

void make_tree(){
szt = 0;
node root(-1, -1, -1); root.link = 0;
t[szt++] = root;

tpos pos(0, 0);
forn(i, szs){
pos = add_char_to_tree(pos, i);
}
}

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

int K;
li result = 0;
typedef tree<pt, null_type,
 less<pt>, rb_tree_tag, 
 tree_order_statistics_node_update> treap;

struct data{
treap* t;
map<int, int>* cnt;
set<int>* positions;

data(){
t = new treap();
cnt = new map<int, int>();
positions = new set<int>();
}

void in_t(int x){
(*cnt)[x]++;
t->insert(mp(x, (*cnt)[x]));
}

void er_t(int x){
t->erase(mp(x, (*cnt)[x]));
(*cnt)[x]--;
}

void insert(int value){
(*positions).insert(value);
set<int>::iterator it = positions->lower_bound(value);

if(it != positions->begin()){
set<int>::iterator prev = it;
prev--;
in_t((*it) - (*prev));
}

if(it != positions->end()){
set<int>::iterator next = it;
next++;
if(next != positions->end()){
in_t((*next) - (*it));
}
}

if(it != positions->begin() && it != positions->end()){
set<int>::iterator prev = it, next = it;
prev--, next++;
if(next != positions->end()){
er_t((*next) - (*prev));
}
}
}

int get_less(int key){
return (int)t->order_of_key(mp(key, -1));
}

void clear(){
t->clear();
cnt->clear();
positions->clear();
}
};

int islands(data t, int ln){
return (int)(t.positions->size() - t.get_less(ln + 1));
}

void dfs(int v, int ln, data& ord){
if(t[v].next.empty()){
ord.insert(szs - ln);
}
data cur;
for(map<char, int>::iterator it = 
t[v].next.begin();
 it != t[v].next.end(); it++){
int u = it->Y;
dfs(u, ln + leng(u), cur);
if(cur.positions->size() > ord.positions->size())
swap(cur, ord);

for(set<int>::iterator jt =
 cur.positions->begin(); 
 jt != cur.positions->end(); jt++){
ord.insert(*jt);
}

cur.clear();
}



if(ln > 0){
int ansL = -1, ansR = -1;
{
int lf = ln - leng(v) + 1, rg = ln;
while(rg - lf > 1){
int mid = (lf + rg) >> 1;
if(islands(ord, mid) > K)
lf = mid;
else
rg = mid;
}
for(int x = lf; x <= rg; x++){
if(islands(ord, x) == K){
ansL = x;
break;
}
}
}
{
int lf = ln - leng(v) + 1, rg = ln;
while(rg - lf > 1){
int mid = (lf + rg) >> 1;
if(islands(ord, mid) < K)
rg = mid;
else
lf = mid;
}
for(int x = rg; x >= lf; --x){
if(islands(ord, x) == K){
ansR = x;
break;
}
}
}
if(ansL != -1){
result += ansR - ansL + 1;

}
}
}

#include <sys/resource.h>

void init_stack(){
const rlim_t kStackSize = 512 * 1024 * 1024;
struct rlimit rl;
int result;

result = getrlimit(RLIMIT_STACK, &rl);
if (result == 0)
{
if (rl.rlim_cur < kStackSize)
{
rl.rlim_cur = kStackSize;
result = setrlimit(RLIMIT_STACK, &rl);
if (result != 0)
{
fprintf(stderr, 
"setrlimit returned result = %d\n", result);
}
}
}
}

int main() {
#ifdef ssu1
assert(freopen("input.txt", "rt", stdin));
#endif

init_stack();

gets(s);
szs = (int)strlen(s);
s[szs++] = '$';

make_tree();

assert(scanf("%d", &K) == 1);

data ord;

dfs(0, 0, ord);

if(K == 1){
result -= szs;
}

cout << result << endl;
#ifdef ssu1
cerr << "\nTime = " << double(
    clock()) / CLOCKS_PER_SEC << endl;
#endif    
return 0;
}









In   Java  :








import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;
import java.util.regex.*;

public class Solution {


public static void main(String[] args) {

Scanner in = new Scanner(System.in);
if(in.hasNext()){
final char[] str = in.next().toCharArray();
if(str.length>0 && in.hasNext()){
int k = in.nextInt();
if(k>0 && k<=str.length){
System.out.println((
new FoundSubStrings(str, k)).count());
}
}
}
}

static class FoundSubStrings {

private final char[] str;
private final int k;
private Map<Long, SubString> curr;
private Map<Long, SubString> next;
private SubString previousSub=null;
private int previousSubParentStartIndex = -1;
private int previousSubLen = -1;

public FoundSubStrings(char[] str, int k) {
this.str = str;
this.k = k;
curr = new HashMap<>(str.length>32 ? 
str.length>>1 : str.length);
next = new HashMap<>(str.length>32 ? 
str.length>>1 : str.length);
}

public long count(){
long countResult = 0;
int startIndex;
char lastChar = str[0];
int lastCharCount = 0;
for(int i=0; i<=str.length; i++){
if(i==str.length || lastChar!=str[i]){
if(lastCharCount>1){
for(int j=i-lastCharCount; j<i-1; j++){
this.add(j, lastChar, i-j);
}
}
this.add(i-1, lastChar);
if(i!=str.length){
lastChar = str[i];
lastCharCount = 1;
}
} else {
lastCharCount++;
}
}
//
this.switchLists();
//
while(!curr.isEmpty()){
for(SubString subStr : curr.values()){
if(subStr.islands==k){
countResult++;
if(k==1 && subStr.size==1){
countResult+=str.length-subStr.startIndex-subStr.len;
continue;
}
} else if(subStr.size<k){
continue;
}
for(int i=0; i<subStr.size && (
    (startIndex=subStr.indexes[i])<(str.length-subStr.len));
     i++){
this.add(subStr.startIndex, startIndex,
 str[startIndex+subStr.len],
  subStr.len+1, subStr.size);
}
}
this.switchLists();
}
return countResult;
}

private void add(int parentStartIndex, 
int startIndex, char chr, int len, int childsLength){
if(previousSubParentStartIndex!=parentStartIndex
 || previousSubLen!=len || previousSub.chr!=chr){
long key = getKey(parentStartIndex, len, chr);
previousSub = next.get(key);
if(previousSub==null){
previousSub = new SubString(parentStartIndex,
 startIndex, chr, len, childsLength);
next.put(key, previousSub);
}
previousSubParentStartIndex = 
previousSub.parentStartIndex;
previousSubLen = len;
}
previousSub.addIndex(startIndex);
}

private void add(int startIndex, char chr, int len){
long key = getKey(len, chr);
SubString sub = next.get(key);
if(sub==null){
sub = new SubString(startIndex, chr, len);
next.put(key, sub);
}
sub.addIndex(startIndex);
}

private void add(int startIndex, char chr){
if(previousSub==null || previousSubLen!=1 || 
previousSub.chr!=chr){
long key = getKey(chr);
previousSub = next.get(key);
if(previousSub==null){
previousSub = new SubString(startIndex, chr, 1);
next.put(key, previousSub);
}
previousSubLen = 1;
}
previousSub.addIndex(startIndex);
}

private void switchLists(){
previousSubParentStartIndex = -1;
previousSub = null;
Map<Long, SubString> tmp = curr;
curr = next;
next = tmp;
tmp.clear();
}


public static long getKey(int parentStartIndex,
 int length, char chr){
return (((long)parentStartIndex) | ((
    long)length<<31) | ((long)chr)<<23);
}

public static long getKey(int length, 
char chr){
return (((long)length<<31) | (((long)chr)<<23));
}

public static long getKey(char chr){
return (((long)chr)<<23);
}

class SubString implements Comparable<SubString> {

private final int parentStartIndex;
private final int len;
private final char chr;
private int startIndex;
private int islands = 0;
//
private int[] indexes;
private int size = 0;

public SubString(int startIndex,
 char chr, int length) {
this(-1, startIndex, chr, length, 16);
}

public SubString(int startIndex, char chr,
 int length, int childsLength) {
this(-1, startIndex, chr, length, childsLength);
}

public SubString(int parentStartIndex,
 int startIndex, char chr, int length, 
 int childsLength) {
this.parentStartIndex = parentStartIndex;
this.startIndex = startIndex;
this.len = length;
this.chr = chr;
this.indexes = new int[
    childsLength>16? 16: childsLength+1];
}

public void addIndex(int index){
if(size==0 || (indexes[size-1]+len<index)){
islands++;
}
if(indexes.length==size+1){
int[] tmpArr = new int[indexes.length<<1];
System.arraycopy(indexes, 0, tmpArr, 0, indexes.length);
indexes = tmpArr;
}
indexes[size++] = index;
}

@Override
public int compareTo(SubString o) {
return (
this.parentStartIndex==o.parentStartIndex) ? chr - o.chr :
this.parentStartIndex - o.parentStartIndex;
}

@Override
public String toString() {
StringBuilder sb = new StringBuilder(100);
sb.append("SubString{startIndex=").append(startIndex).
append(", length=")
.append(len).append(", islands=")
.append(islands).append(", numberOfIndexes=")
.append(size).append(", arr=");
for(int i=startIndex; i<startIndex+len; i++){
sb.append(str[i]).append(',');
}
sb.setCharAt(sb.length()-1,'}');
return sb.toString();
}
}
}
}









In   C  :








#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define A_SIZE 26
#define MIN_C 'a'
typedef struct _st_node st_node;
typedef struct _st_edge st_edge;
typedef enum _type{
ONE=1,
TWO,
BOTH
} type;
struct _st_node{
st_node *suffix_link;
type t;
st_edge *edges[A_SIZE+2];
};
struct _st_edge{
int from;
int to;
int suffix_index;
st_node *node;
};
typedef struct _ct_node{
int size;
int priority;
int value;
struct _ct_node *left,*right;
} ct_node;
int sizeOf(ct_node *root);
void recalc(ct_node *root);
ct_node* merge(ct_node *L,ct_node *R);
void split1(int x,ct_node **L,ct_node **R,ct_node *root);
void split2(int x,ct_node **L,ct_node **R,ct_node *root);
int max(ct_node *root);
int min(ct_node *root);
void insert(ct_node **root,ct_node *t);
void delete(ct_node **root,int x);
void full_insert(ct_node **arr,ct_node **diff,ct_node *t);
void dfs_aux(ct_node **arr,ct_node **diff,ct_node *t);
void dfs(st_node *root,int len_from,
int len_to,int suffix_index,ct_node **arr,ct_node **diff);
void suffix_tree(st_node *root,
char *str,int len,int flag,int offset);
int inter(int l1,int l2,int l3,int l4);
char str[100001];
int k,len;
long long ans;

int main(){
st_node root;
ct_node *r1,*r2;
scanf("%s%d",str,&k);
len=strlen(str);
memset(&root,0,sizeof(st_node));
suffix_tree(&root,str,len,0,0);
dfs(&root,0,0,0,&r1,&r2);
printf("%lld",ans);
return 0;
}
int sizeOf(ct_node *root){
return (root)?root->size:0;
}
void recalc(ct_node *root){
root->size=sizeOf(root->left)+
sizeOf(root->right)+1;
return;
}
ct_node* merge(ct_node *L,ct_node *R){
if(!L)
return R;
if(!R)
return L;
if(L->priority>R->priority){
L->right=merge(L->right,R);
recalc(L);
return L;
}
R->left=merge(L,R->left);
recalc(R);
return R;
}
void split1(int x,ct_node **L,
ct_node **R,ct_node *root){
if(!root){
*L=*R=NULL;
return;
}
int curIndex=sizeOf(root->left);
ct_node *t;
if(curIndex<=x){
split1(x-curIndex-1,&t,R,root->right);
root->right=t;
recalc(root);
*L=root;
}
else{
split1(x,L,&t,root->left);
root->left=t;
recalc(root);
*R=root;
}
return;
}
void split2(int x,ct_node **L,
ct_node **R,ct_node *root){
if(!root){
*L=*R=NULL;
return;
}
int curIndex=root->value;
ct_node *t;
if(curIndex<=x){
split2(x,&t,R,root->right);
root->right=t;
recalc(root);
*L=root;
}
else{
split2(x,L,&t,root->left);
root->left=t;
recalc(root);
*R=root;
}
return;
}
int max(ct_node *root){
if(root->right)
return max(root->right);
return root->value;
}
int min(ct_node *root){
if(root->left)
return min(root->left);
return root->value;
}
void insert(ct_node **root,ct_node *t){
ct_node *t1,*t2;
split2(t->value,&t1,&t2,*root);
*root=merge(t1,merge(t,t2));
return;
}
void delete(ct_node **root,int x){
ct_node *t1,*t2,*t3;
split2(x,&t1,&t3,*root);
split1(sizeOf(t1)-2,&t1,&t2,t1);
*root=merge(t1,t3);
return;
}
void full_insert(ct_node **arr,
ct_node **diff,ct_node *t){
int v1,v2;
ct_node *t1,*t2,*t3;
split2(t->value,&t1,&t2,*arr);
if(!t1 && !t2)
*diff=NULL;
else if(!t1){
v1=min(t2)-t->value;
t3=(ct_node*)malloc(sizeof(ct_node));
t3->priority=rand();
t3->value=v1;
t3->size=1;
t3->left=t3->right=NULL;
insert(diff,t3);
}
else if(!t2){
v1=t->value-max(t1);
t3=(ct_node*)malloc(sizeof(ct_node));
t3->priority=rand();
t3->value=v1;
t3->size=1;
t3->left=t3->right=NULL;
insert(diff,t3);
}
else{
v1=max(t1);
v2=min(t2);
delete(diff,v2-v1);
t3=(ct_node*)malloc(sizeof(ct_node));
t3->priority=rand();
t3->value=t->value-v1;
t3->size=1;
t3->left=t3->right=NULL;
insert(diff,t3);
t3=(ct_node*)malloc(sizeof(ct_node));
t3->priority=rand();
t3->value=v2-t->value;
t3->size=1;
t3->left=t3->right=NULL;
insert(diff,t3);
}
*arr=merge(t1,merge(t,t2));
return;
}
void dfs_aux(ct_node **arr,
ct_node **diff,ct_node *t){
if(!t)
return;
dfs_aux(arr,diff,t->left);
dfs_aux(arr,diff,t->right);
t->size=1;
t->left=t->right=NULL;
full_insert(arr,diff,t);
return;
}
void dfs(st_node *root,int len_from,
int len_to,int suffix_index,
ct_node **arr,ct_node **diff){
int v1,v2,i;
ct_node *p_arr,*p_diff,*pp_arr,*pp_diff,*t1,*t2;
if(!root){
p_arr=(ct_node*)malloc(sizeof(ct_node));
p_arr->priority=rand();
p_arr->value=suffix_index;
p_arr->size=1;
p_arr->left=p_arr->right=NULL;
*arr=p_arr;
*diff=NULL;
return;
}
p_arr=p_diff=NULL;
if(root->edges[A_SIZE]){
dfs(root->edges[A_SIZE]->node,0,0,
root->edges[A_SIZE]->suffix_index,
&pp_arr,&pp_diff);
if(sizeOf(p_arr)<sizeOf(pp_arr)){
dfs_aux(&pp_arr,&pp_diff,p_arr);
p_arr=pp_arr;
p_diff=pp_diff;
}
else
dfs_aux(&p_arr,&p_diff,pp_arr);
}
for(i=0;i<A_SIZE;i++)
if(root->edges[i]){
dfs(root->edges[i]->node,len_to+1,
len_to+root->edges[i]->to-root->edges[i]->from+1,
root->edges[i]->suffix_index,&pp_arr,&pp_diff);
if(sizeOf(p_arr)<sizeOf(pp_arr)){
dfs_aux(&pp_arr,&pp_diff,p_arr);
p_arr=pp_arr;
p_diff=pp_diff;
}
else
dfs_aux(&p_arr,&p_diff,pp_arr);
}
*arr=p_arr;
*diff=p_diff;
if(len_to){
if(sizeOf(p_arr)<k)
return;
split1(sizeOf(p_arr)-k-1,&t1,&t2,p_diff);
if(!t1 && !t2)
ans+=inter(0,100000,len_from,len_to);
else if(!t1)
ans+=inter(0,min(t2)-1,len_from,len_to);
else if(!t2)
ans+=inter(max(t1),100000,len_from,len_to);
else{
v1=max(t1);
v2=min(t2);
if(v1!=v2)
ans+=inter(v1,v2-1,len_from,len_to);
}
p_diff=merge(t1,t2);
}
return;
}
void suffix_tree(st_node *root,
char *str,int len,int flag,int offset){
int a_edge,a_len=0,remainder=0,
need_insert,from,max,i;
type t;
st_node *a_node=root,*pre_node,*t_node,*tt_node,*pp_node=NULL;
st_edge *t_edge;
if(flag){
max=A_SIZE+1;
t=TWO;
}
else{
max=A_SIZE;
t=ONE;
}
root->t|=t;
for(i=offset;i<=offset+len;i++){
need_insert=0;
pre_node=NULL;
remainder++;
if(i==offset+len)
need_insert=1;
else if(a_len)
if(str[a_node->edges[a_edge]->from+a_len]==str[i])
if(a_node->edges[a_edge]->from+
a_len==a_node->edges[a_edge]->to){
a_node=a_node->edges[a_edge]->node;
a_node->t|=t;
a_len=0;
}
else
a_len++;
else
need_insert=1;
else
if(a_node->edges[str[i]-MIN_C])
if(a_node->edges[str[i]-MIN_C]->from==
a_node->edges[str[i]-MIN_C]->to){
a_node=a_node->edges[str[i]-MIN_C]->node;
a_node->t|=t;
}
else{
a_edge=str[i]-MIN_C;
a_len=1;
}
else
need_insert=1;
if(need_insert)
for(;remainder>0;remainder--){
if(!a_len)
if(i==offset+len){
a_node->edges[max]=(st_edge*)malloc(sizeof(st_edge));
a_node->edges[max]->suffix_index=i-remainder+1;
a_node->edges[max]->node=NULL;
t_node=tt_node=a_node;
}
else{
if(a_node->edges[str[i]-MIN_C]){
if(pre_node)
pre_node->suffix_link=a_node;
if(a_node->edges[
str[i]-MIN_C]->from==a_node->edges[str[i]-MIN_C]->to){
a_node=a_node->edges[str[i]-MIN_C]->node;
a_node->t|=t;
}
else{
a_edge=str[i]-MIN_C;
a_len=1;
}
break;
}
t_edge=(st_edge*)malloc(sizeof(st_edge));
t_edge->from=i;
t_edge->to=offset+len-1;
t_edge->suffix_index=i-remainder+1;
t_edge->node=(st_node*)malloc(sizeof(st_node));
memset(t_edge->node,0,sizeof(st_node));
t_edge->node->edges[max]=(st_edge*)malloc(sizeof(st_edge));
t_edge->node->edges[max]->suffix_index=i-remainder+1;
t_edge->node->edges[max]->node=NULL;
t_edge->node->t|=t;
a_node->edges[str[i]-MIN_C]=t_edge;
t_node=a_node;
tt_node=t_edge->node;
}
else{
if(i!=offset+len && str[
    a_node->edges[a_edge]->from+a_len]==str[i]){
if(pre_node)
pre_node->suffix_link=a_node;
if(a_node->edges[a_edge]->from+
a_len==a_node->edges[a_edge]->to){
a_node=a_node->edges[a_edge]->node;
a_node->t|=t;
a_len=0;
}
else
a_len++;
break;
}
t_node=(st_node*)malloc(sizeof(st_node));
memset(t_node,0,sizeof(st_node));
t_node->t|=(a_node->edges[a_edge]->node->t|t);
t_edge=(st_edge*)malloc(sizeof(st_edge));
t_edge->from=a_node->edges[a_edge]->from+a_len;
t_edge->to=a_node->edges[a_edge]->to;
t_edge->suffix_index=a_node->edges[a_edge]->suffix_index;
t_edge->node=a_node->edges[a_edge]->node;
from=a_node->edges[a_edge]->from;
a_node->edges[a_edge]->node=t_node;
a_node->edges[a_edge]->to=a_node->edges[a_edge]->from+a_len-1;
t_node->edges[str[t_edge->from]-MIN_C]=t_edge;
if(i==offset+len){
t_node->edges[max]=(st_edge*)malloc(sizeof(st_edge));
t_node->edges[max]->suffix_index=i-remainder+1;
t_node->edges[max]->node=NULL;
tt_node=t_node;
}
else{
t_edge=(st_edge*)malloc(sizeof(st_edge));
t_edge->from=i;
t_edge->to=offset+len-1;
t_edge->suffix_index=i-remainder+1;
t_edge->node=(st_node*)malloc(sizeof(st_node));
memset(t_edge->node,0,sizeof(st_node));
t_edge->node->edges[max]=(st_edge*)malloc(sizeof(st_edge));
t_edge->node->edges[max]->suffix_index=i-remainder+1;
t_edge->node->edges[max]->node=NULL;
t_edge->node->t|=t;
t_node->edges[str[i]-MIN_C]=t_edge;
tt_node=t_edge->node;
}
}
if(pre_node)
pre_node->suffix_link=t_node;
pre_node=t_node;
if(pp_node)
pp_node->suffix_link=tt_node;
pp_node=tt_node;
if(a_node==root && a_len>0){
if(remainder>1)
a_edge=str[i-remainder+2]-MIN_C;
from=i-remainder+2;
a_len--;
}
else if(a_node!=root)
if(a_node->suffix_link){
a_node=a_node->suffix_link;
a_node->t|=t;
}
else
a_node=root;
while(a_len>0 && a_len>=a_node->edges[
    a_edge]->to-a_node->edges[a_edge]->from+1){
a_len-=a_node->edges[
    a_edge]->to-a_node->edges[a_edge]->from+1;
from+=a_node->edges[
    a_edge]->to-a_node->edges[a_edge]->from+1;
a_node=a_node->edges[
    a_edge]->node;
a_node->t|=t;
a_edge=str[from]-MIN_C;
}
}
}
return;
}
int inter(int l1,int l2,int l3,int l4){
if(l3>l2 || l1>l4)
return 0;
if(l3>=l1)
if(l4>=l2)
return l2-l3+1;
else
return l4-l3+1;
else
if(l4>=l2)
return l2-l1+1;
else
return l4-l1+1;
}









In    Python3 :







from collections import defaultdict


class LetterIslands:
    
    def __init__(self):
        self.s = 0
        self.k = 0
        self.n = 0
        self.result = 0

    def get_indice(self):
        cache = defaultdict(list)
        for (idx,let) in enumerate(self.s):
            cache[let].append(idx)
        for (key,val) in cache.items():
            l = len(val)
            if l < self.k:
                continue
            else:
                for i in range(len(val)-1):
                    if val[i+1] - val[i] <= 1:
                        l -= 1
                if l == self.k:
                    self.result += 1    
        return cache
    
    def get_result(self):
        for (let, pos) in self.get_indice().items():
            len_ = 1
            arr = [[let, pos]]
            while len(arr) > 0:
                dict_ = defaultdict(list)
                temp = []
                for t in arr:
                    for indice in t[1]:
                        try:
                            dict_[t[0] + self.s[indice + len_]].append(indice)
                        except:
                            pass
                len_ = len_+1
                for (key,val) in dict_.items():
                    l = len(val)
                    if l < self.k:
                        continue
                    else:
                        i = 0
                        lenVal = len(val)
                        while l >= self.k and i < lenVal-1:
                            if val[i+1] - val[i] <= len_:
                                l -= 1        
                            i += 1
                        if l == self.k:
                            self.result += 1    
                        if l >= self.k - 1:
                            temp.append([key,val])                
                arr = temp

        return (self.result)


    def debug(self):
        try:
            self.solve()
            print(self.result)
        except:
            pass

    
    def solve(self):
        self._input()
        self.get_result()


    def _input(self):
        self.s = input()
        self.k = int(input()) 
        self.n = len(self.s)


if __name__ == "__main__":
    LetterIslands().debug()