HDU4171--bfs+树

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <queue>
#define INF 2000100000
using namespace std;
typedef long long ll;
const int maxn = 1e5 + 5;

ll d2[maxn];
ll d1[maxn];
int vis[maxn];

struct Edge
{
    int to, len;
} edge[maxn];

struct node
{
    int id, d;
};
vector<Edge> g[maxn];

void bfs(int s)
{
    memset(vis, 0, sizeof(vis));
    memset(d1, 0, sizeof(d1));
    d1[s] = 0;
    vis[s] = 1;
    queue<node> que;
    que.push((node) {
        0, 0
    });
    while(!que.empty())
    {
        node x = que.front();
        que.pop();
        int p = x.id;
        for(int i = 0; i < g[p].size(); ++i)
        {
            Edge &e = g[p][i];
            if(!vis[e.to]) {
                d1[e.to] = d1[p] + e.len;
                vis[e.to] = 1;
                que.push((node) {
                    e.to, d1[e.to]
                });
            }
        }
    }
}
int main()
{
    //freopen("in", "r", stdin);
    int n;
    while(~scanf("%d", &n)) {
        for(int i = 0; i <= n; ++i) scanf("%I64d", d2 + i);
        int from, to, len;
        ll sum = 0;
        for(int i = 0; i < n; ++i)
        {
            scanf("%d%d%d", &from, &to, &len);
            g[from].push_back((Edge) {
                to, len
            });
            g[to].push_back((Edge) {
                from, len
            });
            sum += len;
        }
        sum *= 2;
        bfs(0);
        //for(int i = 0; i <= n; ++i) printf("%d ",d1[i]);
        //printf("\n");
        ll mx = INF;
        for(int i = 0; i <= n; ++i)
        {
            mx = min(mx, sum - d1[i] + d2[i]);
        }
        cout << mx << endl;
        for(int i = 0; i <= n; ++i) g[i].clear();
    }
}