题解 | 【模板】二维前缀和-Java

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        int q = in.nextInt();

        // 原始矩阵使用1-based索引
        long[][] matrix = new long[n + 1][m + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                matrix[i][j] = in.nextLong();
            }
        }

        // 构建前缀和数组
        long[][] prefix = new long[n + 1][m + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                prefix[i][j] = matrix[i][j] + prefix[i - 1][j] + prefix[i][j - 1] - prefix[i - 1][j - 1];
            }
        }

        // 处理查询，直接打印每个结果
        while (q-- > 0) {
            int x1 = in.nextInt();
            int y1 = in.nextInt();
            int x2 = in.nextInt();
            int y2 = in.nextInt();

            long sum = prefix[x2][y2] - prefix[x1 - 1][y2] - prefix[x2][y1 - 1] + prefix[x1 - 1][y1 - 1];
            System.out.println(sum); 
        }
    }
}