MAZE

#include <stdio.h>
#include <queue>
#include <stdlib.h>
#include <string.h>
#define MAX 910

using namespace std;

int n, m, x0, y0;
int result;
typedef struct {
    int x;
    int y;
} POINT;
queue<POINT> q;     // queue for cell

bool maze[MAX][MAX];
bool visited[MAX][MAX];         // visited[i][j] = 1 -> cell (i, j) visited
int level[MAX][MAX];        // level[i][j] shortest distance from state (0, 0) to (i, j)

void output () {
    printf("%d\n", result);
}

void dfs () {

    while (!q.empty()) {
        POINT cur = q.front();
        q.pop();
        int xnextf = cur.x + 1;
        int ynextf = cur.y + 1;
        int xnextb = cur.x - 1;
        int ynextb = cur.y - 1;
        if (xnextf > n || xnextb < 1 || ynextf > m || ynextb < 1) {
            result = level[cur.x][cur.y] + 1;
            return;
        }
        POINT tmp;
        if (!maze[xnextf][cur.y] && !visited[xnextf][cur.y]) {
            tmp.x = xnextf;
            tmp.y = cur.y;
            q.push(tmp);
            level[xnextf][cur.y] = level[cur.x][cur.y] + 1;
            visited[tmp.x][tmp.y] = 1;
        }
        if (!maze[xnextb][cur.y] && !visited[xnextb][cur.y]) {
            tmp.x = xnextb;
            tmp.y = cur.y;
            q.push(tmp);
            level[xnextb][cur.y] = level[cur.x][cur.y] + 1;
            visited[tmp.x][tmp.y] = 1;
        }
        if (!maze[cur.x][ynextf] && !visited[cur.x][ynextf]) {
            tmp.x = cur.x;
            tmp.y = ynextf;
            q.push(tmp);
            level[cur.x][ynextf] = level[cur.x][cur.y] + 1;
            visited[tmp.x][tmp.y] = 1;
        }
        if (!maze[cur.x][ynextb] && !visited[cur.x][ynextb]) {
            tmp.x = cur.x;
            tmp.y = ynextb;
            q.push(tmp);
            level[cur.x][ynextb] = level[cur.x][cur.y] + 1;
            visited[tmp.x][tmp.y] = 1;
        }
    }
    result = -1;
}

void solve () {
    POINT tmp = {x0, y0};
    q.push(tmp);
    level[x0][y0] = 0;
    visited[x0][y0] = 1;
    dfs();
}

void input () {
    scanf("%d%d%d%d", &n, &m, &x0, &y0);
    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j)
            scanf("%d", &maze[i][j]);
    }
    memset(visited, 0, sizeof(visited));
    memset(level, 0, sizeof(level));
}

int main () {
    // freopen("inp", "r", stdin);
    // freopen("out", "w", stdout);
    input();
    solve();
    output();
    return 0;
}