Решение задачи Lines - 2 с Acmp

    #include<iostream>

#include<queue>

using namespace std;

int main() {

	int n,i,j,k,x1,y1,x2,y2,u,v;queue<pair<int,int>>q;

	int x[4]={-1,1,0,0},y[4]={0,0,-1,1};

	cin>>n;int d[n][n],p[n][n];string a[n];

	for(i=0;i<n;++i){cin>>a[i];

		for(j=0;j<n;++j){d[i][j]=1000000000;

		if(a[i][j]=='@'){x1=i;y1=j;}

		else if(a[i][j]=='X'){x2=i;y2=j;}}}

	d[x1][y1]=0; q.push(make_pair(x1,y1));

	while(!q.empty()){i=q.front().first;

		j=q.front().second;q.pop();

		for(k=0;k<4;++k){u=i+x[k];v=j+y[k];

			if(u>=0&&u<n&&v>=0&&v<n&&

			a[u][v]!='O'&&d[u][v]>d[i][j]+1){

			d[u][v]=d[i][j]+1;p[u][v]=k;

			q.push(make_pair(u,v));}}}

	if(d[x2][y2]<1000000000){

		cout<<'Y';i=x2;j=y2;

		while(a[i][j]!='@'){a[i][j]='+';

			k=p[i][j];i-=x[k];j-=y[k];}

		for(i=0;i<n;++i)cout<<endl<<a[i];}

	else cout<<'N';

	return 0;}