UVA - 10891 —— Game of Sum

#include <cstdio>
#include <iostream>
#include <cstring>
using namespace std;

int a[105];
int dp[105][105];
int vis[105][105];

int f(int l, int r) 
{
    if(l > r)    return 0;
    if(vis[l][r])    return dp[l][r];
    
    int ret = 0, sum = 0;
    for(int i=l; i<=r; i++)    ret += a[i];
    
    for(int i=l; i<=r; i++) {
        sum += a[i];
        ret = max(ret, sum - f(i+1, r));
    }
    sum = 0;
    for(int i=r; i>=l; i--) {
        sum += a[i];
        ret = max(ret, sum - f(l, i-1));
    }
    vis[l][r] = 1;
    return dp[l][r] = ret;
}

int main ()
{
    int n;
    
    while(scanf("%d", &n) != EOF && n) {
        for(int i=0; i<n; i++) scanf("%d", &a[i]);
        memset(vis, 0, sizeof(vis));
        printf("%d\n", f(0, n-1));
    }
    return 0;
}