洛谷 P5542 [USACO19FEB]Painting The Barn

题目传送门

解题思路:

二维差分的板子题.题解传送门

AC代码:

 #include<iostream>
 #include<cstdio>

 using namespace std;

 int n,k,cf[][],ans,a[][]; 

 int main() {
     scanf("%d%d",&n,&k);
     for(int i = ;i <= n; i++) {
         int x,y,xx,yy;
         scanf("%d%d%d%d",&x,&y,&xx,&yy);
         cf[x][y]++;
         cf[xx][y]--;
         cf[x][yy]--;
         cf[xx][yy]++;
     }
     for(int i = ;i <= ; i++)
         for(int j = ;j <= ; j++) {
             a[i][j] = a[i-][j] + a[i][j-] - a[i-][j-] + cf[i][j];
             if(a[i][j] == k) ans++;
         }
     printf("%d",ans);
     return ;
 }