HDU 4283 (第k个出场 区间DP)

http://blog.csdn.net/acm_cxlove/article/details/7964594

http://www.tuicool.com/articles/jyaQ7n

http://blog.csdn.net/woshi250hua/article/details/7973824

记忆化搜索(15MS)：

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <cctype>
#include <vector>
#include <iterator>
#include <set>
#include <map>
#include <sstream>
using namespace std;

#define mem(a,b) memset(a,b,sizeof(a))
#define pf printf
#define sf scanf
#define spf sprintf
#define pb push_back
#define debug printf("!\n")
#define INF 10000
#define MAX(a,b) a>b?a:b
#define blank pf("\n")
#define LL long long
#define ALL(x) x.begin(),x.end()
#define INS(x) inserter(x,x.begin())
#define pqueue priority_queue

const int MAXN = 1000 + 5;

int n,m;

int dp[110][110];
int a[110],sum[110];

int solve(int i,int j)
{
    int& ans = dp[i][j];
    if(ans!=-1) return ans;
    if(i>=j) return 0;
    ans = 1<<30;
    for(int k = 1;k<=j-i+1;k++)
    {
        ans = min(ans,solve(i+1,i+k-1)+solve(i+k,j) + (k-1)*a[i] + (sum[j]-sum[i+k-1])*k);
    }
    return ans;
}

int main()
{
    int i,j;
    int t;
    cin>>t;
    while(t--)
    {
        cin>>n;
        sum[0]=0;
        for(i=1;i<=n;i++)
        {
            sf("%d",&a[i]);
            sum[i]=sum[i-1]+a[i];
        }
        mem(dp,-1);
        pf("%d\n",solve(1,n));
    }
    return 0;
}

递推：

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <cctype>
#include <vector>
#include <iterator>
#include <set>
#include <map>
#include <sstream>
using namespace std;

#define mem(a,b) memset(a,b,sizeof(a))
#define pf printf
#define sf scanf
#define spf sprintf
#define pb push_back
#define debug printf("!\n")
#define INF 10000
#define MAX(a,b) a>b?a:b
#define blank pf("\n")
#define LL long long
#define ALL(x) x.begin(),x.end()
#define INS(x) inserter(x,x.begin())
#define pqueue priority_queue

const int MAXN = 1000 + 5;

int n,m;

int dp[110][110];
int a[110],sum[110];

int main()
{
    int i,j;
    int t;
    cin>>t;
    while(t--)
    {
        cin>>n;
        sum[0]=0;
        for(i=1;i<=n;i++)
        {
            sf("%d",&a[i]);
            sum[i]=sum[i-1]+a[i];
        }
        mem(dp,0);
        for(int l = 1;l<=n;l++)
        {
            for(i=1;i<=n-l+1;i++)
            {
                j = i+l-1;
                dp[i][j] = 1<<30;
                for(int k = 1;k<=l;k++)
                {
                    dp[i][j] = min(dp[i][j],dp[i+1][i+k-1] + dp[i+k][j] + (k-1)*a[i] + (sum[j]-sum[i+k-1])*k);
                }
            }
        }
        pf("%d\n",dp[1][n]);

    }
    return 0;
}