63分TLE求助！

#include<bits/stdc++.h>
using namespace std;
int mp[310][310] = {0}, np[50001][3], ans = 999999999;
bool mmp[310][310] = {false};
void dfs(int x, int y, int cnt) {
    if (x >= 301 || y >= 301 || x < 0 || y < 0)return;
    if (mp[x][y] <= cnt)return;
    if (mp[x][y] == 99999999) {
        ans = min(ans, cnt);
        return;
    }
    mmp[x][y] = true;
    dfs(x, y + 1, cnt + 1);
    dfs(x, y - 1, cnt + 1);
    dfs(x + 1, y, cnt + 1);
    dfs(x - 1, y, cnt + 1);
//  mmp[x][y] = false;
}
int main() {
    int m;
    cin >> m;
    fill(mp[0], mp[0] + 310 * 310, 99999999);
    for (int i = 0; i < m; i++) {
        scanf("%d%d%d",&np[i][0],&np[i][1],&np[i][2]);
        mp[np[i][0]][np[i][1]] = min(mp[np[i][0]][np[i][1]], np[i][2]);
        mp[np[i][0] + 1][np[i][1]] = min(np[i][2], mp[np[i][0] + 1][np[i][1]]);
        if (np[i][0] - 1 >= 0)
            mp[np[i][0] - 1][np[i][1]] = min(np[i][2], mp[np[i][0] - 1][np[i][1]]);
        mp[np[i][0]][np[i][1] + 1] = min(np[i][2], mp[np[i][0]][np[i][1] + 1]);
        if (np[i][1] - 1 >= 0)
            mp[np[i][0]][np[i][1] - 1] = min(np[i][2], mp[np[i][0]][np[i][1] - 1]);
    }
//  for (int i = 0; i < 20; i++) {
//      for (int j = 0; j < 20; j++) {
//          if (mp[i][j] == 99)cout << 0 << ' ';
//          else cout << mp[i][j] << ' ';
//      }
//      cout << endl;
//  }
    dfs(0, 0, 0);
    if (ans == 999999999)cout << -1;
    else cout << ans << endl;
    return 0;
}