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 <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;
}
                        


                        Solution in C++ :

In    C ++  :






#include <bits/stdc++.h>
using namespace std ;
std::vector<long long int> g[1000007];
long long int dis[10001];
bool visited[10001] ;
int main()
{
	long long int n ;
	cin >> n ;
	string temp ;
	std::vector<string> v;
    queue<long long int> q;
	for(long long int i=0;i<n;i++)
	{
		cin >> temp ;
		v.push_back(temp) ;
	}
	long long int a,b,c,d,start,end,next,front;
	cin >> a >> b >> c >> d ;
	for(long long int i=0;i<n;i++)
	{
		for(long long int j=0;j<n;j++)
		{
			if(v[i][j]=='.')
			{
				start = i*n+j ;
				for(long long int k=i-1;k>=0;k--)
				{
					if(v[k][j]=='.')
					{
						end = n*k+j ;
						g[start].push_back(end) ;
					}
					else
					{
						break ;
					}
				}
				for(long long int k=i+1;k<n;k++)
                {
                    if(v[k][j] == '.')
                    {
                        end = k*n + j;
                        g[start].push_back(end);
                    }
                    else
                    {
                        break;
                    }
                }
                for(long long int k=j-1;k>=0;k--)
                {
                    if(v[i][k] == '.')
                    {
                        end = i*n+k;
                        g[start].push_back(end);
                    }
                    else
                    {
                        break;
                    }
                }
                for(long long int k=j+1;k<n;k++)
                {
                    if(v[i][k]=='.')
                    {
                        end = i*n + k;
                        g[start].push_back(end);
                    }
                    else
                    {
                        break;
                    }
                }
			}
		}
	}
	start = a*n+b;
    q.push(start);
    visited[start] = 1;
    while(q.empty()==0)
    {
        front = q.front();
        q.pop();
        for(long long int i=0;i<g[front].size();i++)
        {
            next = g[front][i];
            if(visited[next]==0)
            {
                visited[next] = 1;
                dis[next] = dis[front]+1;
                q.push(next);
            }
        }
    }
    cout<<dis[c*n+d] ;
	return 0 ;
}
                    


                        Solution in Java :

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 scan=new Scanner(System.in);
        int n=scan.nextInt();
        char[][] matrix=new char[n][n];
        boolean[] visited=new boolean[n*n];
        int[] parent=new int [n*n];
        for(int i=0;i<n*n;i++)
            {             
            parent[i]=-1;
        }
        for(int i=0;i<n;i++)
            {
            String pattern=scan.next();
            for(int j=0;j<n;j++)
                {
                matrix[i][j]=pattern.charAt(j);
              //System.out.print(matrix[i][j]);
            }
            //System.out.println();
        }
        int a=scan.nextInt();
        int b=scan.nextInt();
        int c=scan.nextInt();
        int d=scan.nextInt();
        int source=n*a+b;
        int des=n*c+d;
        LinkedList<Integer> list=new LinkedList<Integer>();
        list.add(source);
        while(list.size()>0)
            {
            int x=list.remove();
          // System.out.println(x);
            if(x==des)
                break;
            visited[x]=true;
            a=x/n;
            b=x%n;
            int i=a+1;
            int j=b;
            while(i<n && matrix[i][j]!='X')
                {
                if(visited[n*i+j]==false)
                    {
                    list.add(n*i+j);          
                    parent[n*i+j]=x;
                    visited[n*i+j]=true;
                }
                i++;
            }
            i=a-1;
            j=b;
            while(i>=0 && matrix[i][j]!='X')
                {
                if(visited[n*i+j]==false)
                    {
                    list.add(n*i+j);          
                    parent[n*i+j]=x;
                    visited[n*i+j]=true;
                }
                i--;
            }
            i=a;
            j=b+1;
            while(j<n && matrix[i][j]!='X')
                {
                if(visited[n*i+j]==false)
                    {
                    list.add(n*i+j);          
                    parent[n*i+j]=x;
                    visited[n*i+j]=true;
                }
                j++;
            }
            i=a;
            j=b-1;
            while(j>=0 && matrix[i][j]!='X')
                {
                if(visited[n*i+j]==false)
                    {
                    list.add(n*i+j);          
                    parent[n*i+j]=x;
                    visited[n*i+j]=true;
                }
                j--;
            }
        }
        int i=des;
        int count=0;
        while(parent[i]!=-1)
            {
            i=parent[i];
            count++;
        }
        System.out.println(count);
    }
}
                    


                        Solution in Python : 
                            
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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