poj 3253 Fence Repair

贪心，这是挑战程序设计竞赛书上的一种方法，略微奇特的贪心。用到了二叉树的思想，还是很有意思的。

//
//  main.cpp
//  poj 3253
//
//  Created by dada on 2017/2/15.
//  Copyright © 2017年 dada. All rights reserved.
//

#include <iostream>
#include<algorithm>
#define MAX_N 20005
typedef long long ll;

using namespace std;

int n,l[MAX_N];

void solve()
{
    ll ans=0;
    while(n>1)
    {
        int mii1 = 0, mii2 = 1;
        if(l[mii1] > l[mii2])
            swap(mii1,mii2);
        
        for(int i = 2; i < n; i++)
        {
            if(l[i] < l[mii1])
            {
                mii2 = mii1;
                mii1=i;
            }
            else if(l[i] < l[mii2])
            {
                mii2=i;
            }
        }
    
    
        int t = l[mii1]+l[mii2];
        ans+=t;
    
        if(mii1 == n-1)
            swap(mii1,mii2);
        l[mii1] = t;
        l[mii2] = l[n-1];
        n--;
    }
    cout<<ans<<endl;
}
int main()
{
    while(cin>>n)
    {
        for(int i = 0; i < n; i++)
            cin>>l[i];
        solve();
    }
    return 0;
}