区间DP初步

石子合并问题

282. 石子合并

$dp[l][r]=dp[l][k]+dp[k+1][r]+s[r]-s[l-1]$

#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;
const int maxn = 310, INF = 1e9;
int w[maxn],s[maxn],n;
int dp[maxn][maxn];

int main(){
    cin >> n;
    for(int i=1;i<=n;i++) cin >> w[i];
    for(int i=1;i<=n;i++) s[i] = s[i-1]+w[i];
    for(int len = 2;len<=n;len++){
        for(int l = 1;l+len-1<=n;l++){
            int r = l+len-1;
            dp[l][r] = INF;
            for(int k=l;k<r;k++){
                dp[l][r] = min(dp[l][r],dp[l][k]+dp[k+1][r]+s[r]-s[l-1]);
            }
        }
    }
    cout << dp[1][n];
    return 0;
}