POJ 3253 Fence Repair

简单贪心，每次合并长度最小的两段，优先级队列维护一下。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn=20000+10;
int n;
long long a[maxn];
struct cmp1{
    bool operator ()(long long &a,long long &b){
        return a>b;
    }
};
int r;

int main()
{
    while(~scanf("%d",&n))
    {
        priority_queue<long long,vector<long long>,cmp1>q;
        for(int i=1; i<=n; i++)
        {
            scanf("%lld",&a[i]);
            q.push(a[i]);
        }
        r=n-1;
        long long cost=0;
        while(r--)
        {
            long long sum=0;
            sum=sum+q.top();q.pop();
            sum=sum+q.top();q.pop();
            q.push(sum);
            cost=cost+sum;
        }
        printf("%lld\n",cost);
    }
    return 0;
}