uva 10755 - Garbage Heap(最大和问题）

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题目连接：uva 10755 - Garbage Heap

题目大意：给出一个三位矩阵，求说子矩阵和最大值。

解题思路：现将各个平面上的矩阵记录下矩阵和，然后可以枚举二维上的矩阵，映射成三维去做。

#include <stdio.h>#include <string.h>#include <algorithm>using namespace std;typedef long long ll;const int N = 30;const ll INF = 0x3f3f3f3f3f3f3f;int x, y, z;ll g[N][N][N], s[N][N][N];void init() {memset(s, 0, sizeof(s));scanf("%d%d%d", &x, &y, &z);for (int i = 1; i <= x; i++) {for (int j = 1; j <= y; j++) {for (int k = 1; k <= z; k++) {scanf("%lld", &g[i][j][k]);s[j][k][i] = s[j][k-1][i] + s[j-1][k][i] - s[j-1][k-1][i] + g[i][j][k];}}}}ll count(int n, int m, int p, int q, int x) {return s[m][q][x] - s[n][q][x] - s[m][p][x] + s[n][p][x];}ll solve() {ll ans = -INF, dp[N];for (int n = 1; n <= y; n++) {for (int m = n; m <= y; m++) {for (int p = 1; p <= z; p++) {for (int q = p; q <= z; q++) {memset(dp, 0, sizeof(dp));for (int i = 1; i <= x; i++) {ll t = count(n-1, m, p-1, q, i);dp[i] = max(dp[i-1] + t, t);ans = max(dp[i], ans);}}}}}return ans;}int main() {int cas;scanf("%d", &cas);while (cas--) {init();printf("%lld\n", solve());if (cas) printf("\n");}return 0;}

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