18440二维差分

18440二维差分

⭐️难度：中等
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import java.util.Scanner;public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = scanner.nextInt();int m = scanner.nextInt();int q = scanner.nextInt();int[][] a = new int[1010][1010];int[][] b = new int[1010][1010];for (int i = 1; i <= n; i++) {for (int j = 1; j <= m; j++) {a[i][j] = scanner.nextInt();b[i][j] = a[i][j] + a[i-1][j-1] - a[i-1][j] - a[i][j-1]; // 求差分数组}}// 子矩阵求和for (int i = 0; i < q; i++) {int x1 = scanner.nextInt();int y1 = scanner.nextInt();int x2 = scanner.nextInt();int y2 = scanner.nextInt();int d = scanner.nextInt();b[x1][y1] += d;b[x1][y2+1] -= d;b[x2+1][y1] -= d;b[x2+1][y2+1] += d;}// 差分数组求前缀和还原原数组for (int i = 1; i <= n; i++) {for (int j = 1; j <= m; j++) {b[i][j] = b[i][j] - b[i-1][j-1] + b[i-1][j] + b[i][j-1]; // 直接用b数组求前缀和System.out.print(b[i][j]+" ");}System.out.println();}}
}

🐱笔记

背公式，用公式。