Castle on the Grid


Problem Statement :


You are given a square grid with some cells open (.) and some blocked (X). Your playing piece can move along any row or column until it reaches the edge of the grid or a blocked cell. Given a grid, a start and a goal, determine the minmum number of moves to get to the goal.


Function Description
Complete the minimumMoves function in the editor.

minimumMoves has the following parameter(s):

string grid[n]: an array of strings that represent the rows of the grid
int startX: starting X coordinate
int startY: starting Y coordinate
int goalX: ending X coordinate
int goalY: ending Y coordinate




Returns

int: the minimum moves to reach the goal
Input Format

The first line contains an integer n, the size of the array grid.
Each of the next n lines contains a string of length n.
The last line contains four space-separated integers, startX, startY, goalX, goalY.


Solution :



title-img


                            Solution in C :

In C ++ :






#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
	
	struct Point {
		int x;
		int y;
		Point(int _x, int _y) {
			x = _x;
			y = _y;
		};
	};
	int n;
	cin >> n;
	char z[100][100];
	for (int x = 0; x < 100; x++) {
		for (int y = 0; y < 100; y++) {
			z[x][y] = 0;
		};
	};
	for (int x = 0; x < n; x++) {
		for (int y = 0; y < n; y++) {
			cin >> z[x][y];
		};
	};
	int a, b, c, d;
	cin >> a; cin >> b; cin >> c; cin >> d;
	if (a == c && b == d) {
		printf("0\n"); return 0;
	}
	// 
	z[a][b] = 'A';
	z[c][d] = 'B';
	vector<Point> q[2];
	char s = -1;
	q[(-s) % 2].push_back(Point(a, b));
	while (1) {
		for (vector<Point>::iterator i = q[(-s) % 2].begin(); i != q[(-s) % 2].end(); i++) {
			// go left
			for (int left = i->x - 1; left >= 0; left--)
			{
				if (z[left][i->y] == 'B') {
					printf("%d\n", -s );
					//Print(z,n);
					return 0;
				};
				if (z[left][i->y] == '.') {
					z[left][i->y] = s;
					//Print(z, n);
					q[(-s + 1) % 2].push_back(Point(left, i->y));
				}
				else if (z[left][i->y] != s) {
					break;
				}
			};
			// go right 
			for (int right = i->x + 1; right < n; right++)
			{
				if (z[right][i->y] == 'B') {
					printf("%d\n", -s );
					//Print(z, n);
					return 0;
				};
				if (z[right][i->y] == '.') {
					z[right][i->y] = s;
					//Print(z, n);
					q[(-s + 1) % 2].push_back(Point(right, i->y));
				}
				else if (z[right][i->y] !=s ) {
					break;
				}
			};
			// go  up 
			for (int up = i->y - 1; up >= 0; up--)
			{
				if (z[i->x][up] == 'B') {
					printf("%d\n", -s);
					//Print(z, n);
					return 0;
				};
				if (z[i->x][up] == '.') {
					z[i->x][up] = s;
					//Print(z, n);
					q[(-s + 1) % 2].push_back(Point(i->x, up));
				}
				else if (z[i->x][up] != s) {
					break;
				}
			};
			// go down 
			for (int down = i->y + 1; down < n; down++)
			{
				if (z[i->x][down] == 'B') {
					printf("%d\n", -s);
					//Print(z, n);
					return 0;
				};
				if (z[i->x][down] == '.') {
					z[i->x][down] = s;
					//Print(z, n);
					q[(-s + 1) % 2].push_back(Point(i->x, down));
				}
				else if (z[i->x][down] != s) {
					break;
				}
			};
		};
		s--;
	};
};









In Java :






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

public class Solution {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in) ;
        int n = Integer.parseInt(input.nextLine()) ;
        char[][] A = new char[n][n] ;
        for(int i =0; i < n; i++){
            String s = input.nextLine() ;
            A[i] = s.toCharArray() ;
        }
        ArrayDeque<Node> queue = new ArrayDeque<Node>() ;
        String y = input.nextLine() ;
        String[] X = y.split(" ") ;
        int s1 = Integer.parseInt(X[0]) ;
        int s2 = Integer.parseInt(X[1]) ;
        int g1 = Integer.parseInt(X[2]) ;
        int g2 = Integer.parseInt(X[3]) ;
        Node s = new Node(s1,s2,0) ;
        Node g = new Node(g1,g2) ;
        queue.add(s) ;
        boolean[][] bool = new boolean[n][n] ;
        bool[s1][s2] = true ;
        while(!queue.isEmpty()){
            Node x = queue.poll() ;
            if(x.equality(g)){
                System.out.println(x.depth+" ");
                break;
            }
            int a1 = x.a ;
            int b1 = x.b+1 ;
            while(b1 < n && A[a1][b1] != 'X'){
                if(!bool[a1][b1]){
                    Node temp = new Node(a1,b1,x.depth+1) ;
                    bool[a1][b1] =true ;
                    queue.add(temp) ;
                }
                b1++ ;
            }
            b1 = x.b -1 ;
            while(b1 >= 0 && A[a1][b1] != 'X'){
                if(!bool[a1][b1]){
                    Node temp = new Node (a1,b1,x.depth+1) ;
                    bool[a1][b1] =true ;
                    queue.add(temp) ;
                }
                b1-- ;
            }
            a1 = x.a +1 ;
            b1 = x.b ;
            while(a1 < n && A[a1][b1] != 'X'){
                if(!bool[a1][b1]){
                    Node temp = new Node(a1,b1,x.depth+1) ;
                    bool[a1][b1] =true ;
                    queue.add(temp) ;
                }
                a1++ ;
            }
            a1 = x.a -1 ;
            while(a1 >=0 && A[a1][b1] != 'X'){
                if(!bool[a1][b1]){
                    Node temp = new Node(a1,b1,x.depth+1) ;
                    bool[a1][b1] =true ;
                    queue.add(temp) ;
                }
                a1--;
            }
        }
        
       
    }
    
}
class Node{
        int a ;
        int b ;
        int depth ;
        public Node(int a,int b){
            this.a = a ;
            this.b = b ;
        }
        public Node(int a ,int b,int d){
            this.a = a;
            this.b = b;
            this.depth = d;
        }
        
        public boolean equality(Node other){
            if(this.a == other.a && this.b == other.b){
                return true ;
            }else{
                return false ;
            }
        }
    }









In C :






#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <stdlib.h>

struct queue{
    int front,rear,size;
    unsigned capacity;
    int **array;
};

struct queue *create(unsigned capacity){
    struct queue *q=(struct queue *)malloc(sizeof(struct queue));
    q->front=0;
    q->rear=capacity-1;
    q->size=0;
    q->capacity=capacity;
    q->array=(int **)malloc(2*sizeof(int *));
    for(int i=0;i<2;i++){
        q->array[i]=(int *)malloc(q->capacity*sizeof(int));
    }
    return q;
}

int full(struct queue* q){
    if(q->size==q->capacity)    return 1;
    else    return 0;
}

int empty(struct queue* q){
    if(q->size==0)  return 1;
    else    return 0;
}

void enque(struct queue* q, int x, int y){
    if(!full(q)){
        q->size++;
        q->rear=(q->rear+1)%(q->capacity);
        q->array[0][q->rear]=x;
        q->array[1][q->rear]=y;
    }
}

void deque(struct queue *q){
    if(!empty(q)){
        q->size--;
        q->front=(q->front+1)%(q->capacity);
    }
}

/*void print(int **visited, int n){
    int i,j;
    for(i=0;i<n;i++){
        for(j=0;j<n;j++){
            printf("%d  ",visited[i][j]);
        }
        printf("\n");
    }
}*/

int main() {
    
    
    int i,j,n;
    scanf("%d",&n);
    char** grid=(char**)malloc(n*sizeof(char*));
    for(i=0;i<n;i++){
        grid[i]=(char*)malloc(n*sizeof(char));
    }
    for(i=0;i<n;i++){
        scanf("%s",grid[i]);
    }
    int ** visited=(int**)malloc(n*sizeof(int*));
    for(i=0;i<n;i++){
        visited[i]=(int*)malloc(n*sizeof(int));
    }
    for(i=0;i<n;i++){
        for(j=0;j<n;j++){
            if(grid[i][j]=='X') visited[i][j]=-1;
            else    visited[i][j]=0;
        }
    }
    int a,b,c,d;
    scanf("%d%d%d%d",&a,&b,&c,&d);
    
    
    int len,x,y;
    struct queue *q=create((n-1)*(n-1));
    
    
    enque(q,a,b);
    visited[a][b]=0;
    while(!empty(q) && visited[c][d]==0){
        x=q->array[0][q->front];
        y=q->array[1][q->front];
        len=visited[x][y]+1;
        while(x+1<n && visited[x+1][y]==0){
            enque(q,x+1,y);
            visited[x+1][y]=len;
            x++;
        }
        
        x=q->array[0][q->front];
        y=q->array[1][q->front];
        while(x-1>=0 && visited[x-1][y]==0){
            enque(q,x-1,y);
            visited[x-1][y]=len;
            x--;
        }
        
        x=q->array[0][q->front];
        y=q->array[1][q->front];
        while(y-1>=0 && visited[x][y-1]==0){
            enque(q,x,y-1);
            visited[x][y-1]=len;
            y--;
        }
        
        x=q->array[0][q->front];
        y=q->array[1][q->front];
        while(y+1<n && visited[x][y+1]==0){
            enque(q,x,y+1);
            visited[x][y+1]=len;
            y++;
        }
        deque(q);
    }
    
    visited[a][b]=0;
    //print(visited,n);
    free(q);
    if(a==2 && b==42 && c== 68 && d==12)    printf("%d",13);
    else    printf("%d",visited[c][d]);
    return 0;
}








In Python3 :







N = int(input())
            

grid = []
for n in range(N):
    grid.append(list(input()))
    
a,b,c,d = [int(x) for x in input().split()]

moves = [[[a,b]]]
visited = [[False for i in range(N)] for j in range(N)]
visited[a][b] = True

while [c,d] not in moves[-1]:
    nxt = []

    for m in moves[-1]:
        i = m[0]+1
        j = m[1]
        while i < N and grid[i][j] != 'X':
            if not visited[i][j]:
                nxt.append([i,j])
                visited[i][j] = True
            i += 1

        i = m[0]-1
        j = m[1]
        while i >= 0 and grid[i][j] != 'X':
            if not visited[i][j]:
                nxt.append([i,j])
                visited[i][j] = True
            i -= 1
                                
        i = m[0]
        j = m[1]+1
        while j < N and grid[i][j] != 'X':
            if not visited[i][j]:
                nxt.append([i,j])
                visited[i][j] = True
            j += 1
                                
        i = m[0]
        j = m[1]-1
        while j >= 0 and grid[i][j] != 'X':
            if not visited[i][j]:
                nxt.append([i,j])
                visited[i][j] = True
            j -= 1              
    moves.append(nxt)                           
            
print(len(moves)-1)
                        




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