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31 lines
1.0 KiB
31 lines
1.0 KiB
#include <bits/stdc++.h>
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using namespace std;
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const int N = 130;
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int n;
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int a[N][N]; // 存储题目中的矩阵
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int s[N][N]; // 二维前缀和
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// O(N^4)算法
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int main() {
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cin >> n;
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for (int i = 1; i <= n; i++) {
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for (int j = 1; j <= n; j++) {
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cin >> a[i][j];
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s[i][j] = s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1] + a[i][j];
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}
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}
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int mx = INT_MIN; // 存储答案
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// 遍历左上角坐标，与，右下角坐标
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for (int x1 = 1; x1 <= n; x1++) {
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for (int y1 = 1; y1 <= n; y1++) {
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for (int x2 = 1; x2 <= n; x2++)
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for (int y2 = 1; y2 <= n; y2++) {
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if (x2 < x1 || y2 < y1) continue; // 如果左上角比右下角还要大，就不用求了，下一个
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mx = max(mx, s[x2][y2] + s[x1 - 1][y1 - 1] - s[x2][y1 - 1] - s[x1 - 1][y2]); // 求最大值
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}
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}
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}
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cout << mx << endl; // 输出
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return 0;
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} |