最大子矩阵和 URAL 1146 Maximum Sum

 

题目传送门

 1 /*  2  最大子矩阵和：把二维降到一维，即把列压缩；然后看是否满足最大连续子序列；  3  好像之前做过，没印象了，看来做过的题目要经常看看:)  4 */  5 #include <cstdio>  6 #include <iostream>  7 #include <cstring>  8 #include <algorithm>  9 using namespace std; 10 11 const int MAXN = 1e2 + 10; 12 const int INF = 0x3f3f3f3f; 13 int a[MAXN][MAXN]; 14 int dp[MAXN][MAXN][MAXN]; 15 16 int main(void) //URAL 1146 Maximum Sum 17 { 18 //freopen ("D.in", "r", stdin); 19 20 int n; 21 while (scanf ("%d", &n) == 1) 22  { 23 int ans = -INF; 24 memset (dp, 0, sizeof (dp)); 25 for (int i=1; i<=n; ++i) 26  { 27 for (int j=1; j<=n; ++j) 28  { 29 scanf ("%d", &a[i][j]); 30  } 31  } 32 33 for (int i=1; i<=n; ++i) 34  { 35 for (int j=1; j<=n; ++j) 36  { 37 int sum = 0; 38 for (int k=j; k>=1; --k) 39  { 40 sum += a[i][k]; 41 dp[i][j][k] = max (sum + dp[i-1][j][k], sum); 42 ans = max (ans, dp[i][j][k]); 43  } 44  } 45  } 46 47 printf ("%d\n", ans); 48  } 49 50 return 0; 51 }