bzoj2101: [Usaco2010 Dec]Treasure Chest 藏宝箱

题目链接

bzoj2101: [Usaco2010 Dec]Treasure Chest 藏宝箱

题解

dp

代码

#include<bits/stdc++.h> 
using namespace std; 

inline int read() { 	
    int x = 0,f = 1; 
    char c = getchar(); 
    while(c < '0' || c >'9') c = getchar(); 
    while(c <= '9' && c >= '0') x = x * 10 + c- '0',c = getchar(); 
    return x * f; 
} 
const int maxn = 5005; 
int c[maxn],dp[2][maxn][2],n; 
int main() { 
    n = read(); for(int i = 1;i <= n;++ i) c[i] = read();  
    int now = 0; 
    for(int i = n;i >= 1;i --) { 
        now ^= 1; 
        memset(dp[now],0,sizeof dp[now]) ; 
        for(int j = 1;j <= n;++ j) dp[now][j][0] = dp[now][j][1] = 0; 
        for(int j = i;j <= n;++ j) { 
            dp[now][j][0] = max(dp[now ^ 1][j][1] + c[i],dp[now][j - 1][1] + c[j]); 
            dp[now][j][1] = min(dp[now ^ 1][j][0],dp[now][j - 1][0]);  
        } 
    } 
    printf("%d
",dp[now][n][0]); 
    return 0; 
}