fudq's AC Road

/*
 * fudq.cpp
 *
 *  Created on: 2013-08-07
 *      Author: fudq
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;

#define FOR(i,a) for((i)=0;i<(a);(i)++)
#define MEM(a) (memset((a),0,sizeof(a)))
#define LL __int64

const int N=100010;
const int M=1000010;
const int MOD=1000000007ll;
const int INF=0x7fffffff;
const double eps=1e-7;
const double PI=acos(-1.0);

double f[N];

bool cmp(double a,double b)
{
    if(a>b)
        return true;
    return false;
}

int main()
{
#ifndef ONLINE_JUDGE
    freopen("testin.txt","r",stdin);
//  freopen("testout.txt","w",stdout);
#endif
    int n,m,a,b;
    double c;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(int i=1;i<=n;i++)
            scanf("%lf",&f[i]);
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%lf",&a,&b,&c);
            f[a]+=c/2;
            f[b]+=c/2;
        }
        sort(f+1,f+n+1,cmp);
        double ans=0;
        for(int i=1;i<=n;i+=2)
        {
            if(i+1 <= n)
                ans+=(f[i]-f[i+1]);
            else
                ans+=f[i];
        }
        printf("%.0lf\n",ans);//为防止精度损失，不能写成printf("%d\n",(int)ans);，前者是四舍五入，后者是去尾
    }
    return 0;
}