UVa 10891 Game of Sum / 记忆化搜索

记忆化搜索

dp[i][j] 表示第i~j个元素组成的子序列 先手得分的最大值

dp[i][j] = sum(i,j) - min(dp[i+1][j],dp[i+2][j],.....dp[j][j],dp[i][j-1],dp[i][j-2],.....dp[i][i],0) ,0 代表取完所有数

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAX = 110;int dp[MAX][MAX];bool vis[MAX][MAX];int a[MAX];int sum[MAX];int dfs(int s,int e){if(vis[s][e])return dp[s][e];vis[s][e] = true;int k;int m = 0;for(k = s + 1; k <= e; k++)m = min(m,dfs(k,e));for(k = s; k < e; k++)m = min(m,dfs(s,k));dp[s][e] = sum[e] - sum[s-1] - m;return dp[s][e];}int main(){int n;int i;while(scanf("%d",&n),n){for(i = 1;i <= n; i++){scanf("%d",&a[i]);sum[i] = sum[i-1] + a[i];}memset(vis,false,sizeof(vis));printf("%d\n",2*dfs(1,n)-sum[n]);}return 0;}