ch_5301 石子合并

区间dp板题

#include<iostream>
#include<cstdio>

#define ri register int
#define u int

namespace opt {

    inline u in() {
        u x(0),f(1);
        char s(getchar());
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }

}

using opt::in;

#define NN 305

#include<algorithm>
#include<cstring>

namespace mainstay {

    u N,a[NN],f[NN][NN];

    inline void solve() {
        N=in(),memset(f,0x3f,sizeof(f));
        for(ri i(1);i<=N;++i) a[i]=a[i-1]+in(),f[i][i]=0;
        for(ri len(2);len<=N;++len){
            for(ri l(1);l+len-1<=N;++l){
                u r(l+len-1);
                for(ri k(l);k<r;++k){
                    f[l][r]=std::min(f[l][r],f[l][k]+f[k+1][r]);
                }
                f[l][r]+=a[r]-a[l-1];
            }
        }
        std::cout<<f[1][N];
    }

}

int main() {

    //freopen("x.txt","r",stdin);
    std::ios::sync_with_stdio(false);
    mainstay::solve();

}