20分求调

#include<bits/stdc++.h>
using namespace std;
const int m = 1005;
int a[m][m] = {0};
int d[m][m] = {0};
int n, m;
int main(){
    scanf("%d%d",&n,&m);
    for (int i = 0; i < m; i++) {
        int x1, y1, x2, y2;
        scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
        int nx2 = min(x2 + 1, n);
        int ny2 = min(y2 + 1, n);
        d[x1][y1]++;
        d[x1][ny2]--;
        d[nx2][y1]--;
        d[nx2][ny2]++;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            a[i][j]=d[i][j]+a[i-1][j]+a[i][j-1]-a[i-1][j-1];
            printf("%d ",a[i][j]);
        }
        printf("\n");
    }
    return 0;
}