# Swap Characters Once to Minimize Differences - Google Top Interview Questions

### Problem Statement :

You are given two lowercase alphabet strings s and t of the same length.

Given that you can make at most one swap between two characters in s, return the minimum number of indices where s[i] ≠ t[i].

Constraints

1 ≤ n ≤ 100,000 where n is the length of s and t

Example 1

Input

s = "abbz"

t = "zcca"

Output

2

Explanation

We can swap "a" and "z" to turn s into "zbba". Then there's 2 characters that differ between t.

Example 2

Input
s = "zfba"

t = "zbca"

Output

1

Explanation

We can swap "f" and "b" to turn s into "zbfa". Then there's only 1 character that differ between t.

Example 3

Input

s = "abc"

t = "abc"

Output

0

Explanation

We don't need to swap since all the characters in s already match with t.

### Solution :

Solution in C++ :

const int Z = 26;

int mismatched[Z];

int solve(string s, string t) {
memset(mismatched, 0, sizeof(mismatched));
int mismatched_pairs = 0;
for (int i = 0; i < (int)s.size(); i++) {
mismatched_pairs += s[i] != t[i];
if (s[i] != t[i]) mismatched[s[i] - 'a'] |= 1 << (t[i] - 'a');
}

bool can_swap_one = false;
for (int i = 0; i < Z; i++) {
if (!mismatched[i]) continue;
int i_bit = 1 << i;
for (int j = 0; j < Z; j++) {
if ((mismatched[i] & (1 << j)) && (mismatched[j] & i_bit)) return mismatched_pairs - 2;
can_swap_one |= mismatched[j] & i_bit;
}
}

return mismatched_pairs - can_swap_one;
}

Solution in Java :

import java.util.*;

class Solution {
public int solve(String a, String b) {
int N = a.length();
boolean[][] occ = new boolean[26][26];
int ans = 0;
boolean[] inA = new boolean[26];
boolean[] inB = new boolean[26];
for (int i = 0; i < N; i++) {
int v1 = a.charAt(i) - 'a';
int v2 = b.charAt(i) - 'a';
if (v1 != v2) {
ans++;
occ[v1][v2] = true;
inA[v1] = true;
inB[v2] = true;
}
}
for (int i = 0; i < 26; i++) {
for (int j = i + 1; j < 26; j++) {
if (occ[i][j] && occ[j][i]) {
// there exists indices where letters i and j can be swapped.
return ans - 2;
}
}
}

for (int i = 0; i < 26; i++) {
if (inA[i] && inB[i]) {
// a swap exists to get a pair of letter i.
return ans - 1;
}
}

return ans;
}
}

Solution in Python :

class Solution:
def solve(self, s, t):
ans = 0
for (a, b) in zip(s, t):
if a == b:
continue
ans += 1
return ans - 2
for ch in ascii_lowercase:
return ans - 1
return ans

## Maximum Element

You have an empty sequence, and you will be given N queries. Each query is one of these three types: 1 x -Push the element x into the stack. 2 -Delete the element present at the top of the stack. 3 -Print the maximum element in the stack. Input Format The first line of input contains an integer, N . The next N lines each contain an above mentioned query. (It is guaranteed that each

## Balanced Brackets

A bracket is considered to be any one of the following characters: (, ), {, }, [, or ]. Two brackets are considered to be a matched pair if the an opening bracket (i.e., (, [, or {) occurs to the left of a closing bracket (i.e., ), ], or }) of the exact same type. There are three types of matched pairs of brackets: [], {}, and (). A matching pair of brackets is not balanced if the set of bra

## Equal Stacks

ou have three stacks of cylinders where each cylinder has the same diameter, but they may vary in height. You can change the height of a stack by removing and discarding its topmost cylinder any number of times. Find the maximum possible height of the stacks such that all of the stacks are exactly the same height. This means you must remove zero or more cylinders from the top of zero or more of

## Game of Two Stacks

Alexa has two stacks of non-negative integers, stack A = [a0, a1, . . . , an-1 ] and stack B = [b0, b1, . . . , b m-1] where index 0 denotes the top of the stack. Alexa challenges Nick to play the following game: In each move, Nick can remove one integer from the top of either stack A or stack B. Nick keeps a running sum of the integers he removes from the two stacks. Nick is disqualified f

## Largest Rectangle

Skyline Real Estate Developers is planning to demolish a number of old, unoccupied buildings and construct a shopping mall in their place. Your task is to find the largest solid area in which the mall can be constructed. There are a number of buildings in a certain two-dimensional landscape. Each building has a height, given by . If you join adjacent buildings, they will form a solid rectangle

## Simple Text Editor

In this challenge, you must implement a simple text editor. Initially, your editor contains an empty string, S. You must perform Q operations of the following 4 types: 1. append(W) - Append W string to the end of S. 2 . delete( k ) - Delete the last k characters of S. 3 .print( k ) - Print the kth character of S. 4 . undo( ) - Undo the last (not previously undone) operation of type 1 or 2,