E-Olymp 1060

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define SZ(X) ((int)(X).size())

pair<int,int> que[10000];
int head=0, tail=0;

bool grid[40][40];
char out[40][40];
pair<int,int> back[40][40];
int dx[] = {0,1,0,-1};
int dy[] = {1,0,-1,0};

int32_t main(){
    int n;
    cin >> n;
    pair<int,int> s,e;
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            char c;
            cin >> c;
            if(c == 'X')s = make_pair(i,j);
            else if(c == '@')e = make_pair(i,j);
            if(c == 'O')grid[i][j] = 1;
            else grid[i][j] = 0;
            out[i][j] = c;
        }
    }
    back[s.first][s.second] = make_pair(-1,-1);
    grid[s.first][s.second] = 1;
    que[tail++] = s;
    bool yes = 0;
    while(tail - head > 0 && !yes){
        pair<int,int> tmd = que[head++];
        if(tmd == e)break;
        for(int i = 0; i < 4 && !yes; ++i){
            int nx = tmd.first+dx[i];
            int ny = tmd.second+dy[i];
            if(0 <= nx && nx < n && 0 <= ny && ny < n && !grid[nx][ny]){
                back[nx][ny] = tmd;
                que[tail++] = make_pair(nx,ny);
                grid[nx][ny] = 1;
                if(make_pair(nx, ny) == e)yes = 1;
            }
        }
    }
    if(yes){
        cout << 'Y' << '\n';
        while(e != s){
            e = back[e.first][e.second];
            out[e.first][e.second] = '+';
        }
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < n; ++j)cout << out[i][j];
            cout << '\n';
        }
    }else cout << 'N' << '\n';
    return 0;
}