湖大训练赛4 Dwarf Tower

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Dwarf TowerTime Limit: 2000ms, Special Time Limit:5000ms, Memory Limit:65536KBTotal submit users: 43, Accepted users: 26Problem 12847 : No special judgementProblem description

Little Vasya is playing a new game named “Dwarf Tower”. In this game there are n different items, which you can put on your dwarf character. Items are numbered from 1 to n. Vasya wants to get the item with number 1.
There are two ways to obtain an item:
• You can buy an item. The i-th item costs ci money.
• You can craft an item. This game supports only m types of crafting. To craft an item, you give two particular different items and get another one as a result.
Help Vasya to spend the least amount of money to get the item number 1.

Input

The first line of input contains two integers n and m (1 ≤ n ≤ 10 000; 0 ≤ m ≤ 100 000) — the number of different items and the number of crafting types.
The second line contains n integers ci — values of the items (0 ≤ ci ≤ 109).
The following m lines describe crafting types, each line contains three distinct integers ai, xi, yi — ai is the item that can be crafted from items xi and yi (1 ≤ ai; xi; yi ≤ n; ai ̸= xi; xi ̸= yi; yi ̸= ai).

Output

The output should contain a single integer — the least amount of money to spend.

Sample Input

5 35 0 1 2 55 2 34 2 31 4 53 12 2 11 2 3

Sample Output

刚开始比赛一直很顺，这题开始用暴力T了一发，准备用DFS继续撸一发，队友过来说是树形Dp，思想跟我差不多，好吧，然后嘴贱的顺便丢了一句：如果不是树形DP，接下来不会卡题4个小时吧？（当时对于这种神预测，我表示有种不祥的预感）。果然很快的月神就WR了。我然后修改了一下加入了回朔，不出所料T了。然后一直在想这种思路怎么了，哪里有bug。其实就是不能这样。然后一边开启群嘲模式。ORz...后来我又用了各种优美的姿势暴力破解，最小生成树，拓扑。。。结果都是T。无奈还被大一新生给压下来了。据说不用任何算法。呵呵。临近比赛结束实在忍不住好奇去求教了一下。看到她们居然是用按第一个数排序从小到大，然后按第一个数从大到小更新值。居然AC了。显然这是有问题，我随便出了一组数据给他们。然后无言以对。我也就无语了，这样的煞笔代码也能AC.我当然是针对这代码，没有指人，不要见怪。整场4个小时我们就一直纠结这题。姿势优美却A不了C。煞笔代码却能AC，这种情况碰到几次了，还有一次是在上一次的bestcoder。太伤了。深深感受的这游戏满满的恶意。后来，也就是晚上。月神提出了一个想法，构图的方法跟我类似，不过更新点的时候是用迪杰斯特拉的思想，我提出了几点建议，但是我还是T怕了，反正闲着也是蛋疼，就顺手敲了一下，提交。红色的AC！！！oh...my god!终于在月神的光环下，以正确的姿势AC了。人生无憾了。可以滚去睡觉了。代码就只贴AC的算了。。。心太伤。。。

#include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>#include <iostream>#include <cmath>#include <queue>#include <map>#include <stack>#include <list>#include <vector>using namespace std;#define LL __int64struct node{int x,y;node(LL a,LL b):x(a),y(b){}};LL a[100010];int vis[100010];vector <node>v[10010];int n,m,i,j,k,x,y;queue<int>q;int main(){scanf("%d%d",&n,&m);for (i=1;i<=n;i++){scanf("%I64d",&a[i]);vis[i]=0;}if (m==0){printf("%I64d\n",a[1]);return 0;}for (i=1;i<=m;i++){scanf("%d%d%d",&k,&x,&y);v[x].push_back(node(y,k));v[y].push_back(node(x,k));if (!vis[x]){vis[x]=1;q.push(x);}if (!vis[y]){vis[y]=1;q.push(y);}}while (!q.empty()){k=q.front();vis[k]=0;q.pop();int l=v[k].size();for (i=0;i<l;i++){if (a[k]+a[v[k][i].x]<a[v[k][i].y]){a[v[k][i].y]=a[k]+a[v[k][i].x];if (!vis[v[k][i].y]){q.push(v[k][i].y);vis[v[k][i].y]=1;}}}}printf("%I64d\n",a[1]);return 0;}

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