Java实现子矩阵的和(前缀和)_求矩阵所有子矩阵价值之和java编程

import java.util.*;

public class Main{
    static int N = 1005;
    static int[][] f = new int[N][N];
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();//n行
        int m = in.nextInt();//m列
        int q = in.nextInt();//查询矩阵个数
        for(int i=1;i<=n;i++){
            for(int j=1;j<=m;j++){
                int x = in.nextInt();
                f[i][j]=f[i-1][j]+f[i][j-1]-f[i-1][j-1]+x;
            }
        }
        for(int i=1;i<=q;i++){
            int res=0;
            int x1 = in.nextInt();//矩阵开始坐标
            int y1 = in.nextInt();
            int x2 = in.nextInt();//结束坐标
            int y2 = in.nextInt();
            //System.out.println(f[x2][y2]+" "+f[x1-1][y2]+" "+f[x2][y1-1]);
            res+=(f[x2][y2]-f[x1-1][y2]-f[x2][y1-1]+f[x1-1][y1-1]);//要加上重复减去的
            System.out.println(res);
        }
        
    }
}
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