[day3] reconstruction of roads

Reconstruction of roads

---

Their thinking

$bfs$ , Damaged road negative edge right , Undamaged $0$ .（ Even heard $dfs$ Can run ）

code

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;

int n,m,d;
int st,ed;
int v[110];
int f[100010];
int minn[110];
int a[110][110];
int flg[110][110];

void bfs()
{
    
	f[1]=st;
	memset(minn,0x3f3f3f3f,sizeof(minn));
	minn[st]=0;
	int hd=0,tl=1;
	while(hd<tl)
	{
    
		hd++;
		int x=f[hd];
		for(int i=1;i<=n;i++)
		{
    
			if(minn[x]+a[x][i]<minn[i])
			{
    
				minn[i]=minn[x]+a[x][i];
				if(!v[i])
					v[i]=1,f[++tl]=i;
			}
		}
		v[x]=0;
	}
}

int main()
{
    
	freopen("road.in","r",stdin);
	freopen("road.out","w",stdout);
	cin>>n>>m;
	memset(a,0x3f3f3f3f,sizeof(a));
	for(int i=1;i<=m;i++)
	{
    
		int x,y,z;
		scanf("%d%d%d",&x,&y,&z);
		a[x][y]=a[y][x]=z;
	}
	cin>>d;
	for(int i=1;i<=d;i++)
	{
    
		int x,y;
		scanf("%d%d",&x,&y);
		flg[x][y]=flg[y][x]=1;
	}
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			if(!flg[i][j]&&a[i][j]!=0x3f3f3f3f)
				a[i][j]=0;
	cin>>st>>ed;
	bfs();
	cout<<minn[ed]<<endl;
}