Codeforces Round #286 (Div. 2) B. Mr. Kitayuta's Colorful Graph dfs
1 second
256 megabytes
standard input
standard output
Mr. Kitayuta has just bought an undirected graph consisting of n vertices and m edges. The vertices of the graph are numbered from 1 to n. Each edge, namely edge i, has a color ci, connecting vertex ai and bi.
Mr. Kitayuta wants you to process the following q queries.
In the i-th query, he gives you two integers — ui and vi.
Find the number of the colors that satisfy the following condition: the edges of that color connect vertex ui and vertex vi directly or indirectly.
The first line of the input contains space-separated two integers — n and m (2 ≤ n ≤ 100, 1 ≤ m ≤ 100), denoting the number of the vertices and the number of the edges, respectively.
The next m lines contain space-separated three integers — ai, bi (1 ≤ ai < bi ≤ n) and ci (1 ≤ ci ≤ m). Note that there can be multiple edges between two vertices. However, there are no multiple edges of the same color between two vertices, that is, if i ≠ j,(ai, bi, ci) ≠ (aj, bj, cj).
The next line contains a integer — q (1 ≤ q ≤ 100), denoting the number of the queries.
Then follows q lines, containing space-separated two integers — ui and vi (1 ≤ ui, vi ≤ n). It is guaranteed that ui ≠ vi.
For each query, print the answer in a separate line.
4 5
1 2 1
1 2 2
2 3 1
2 3 3
2 4 3
3
1 2
3 4
1 4
2
1
0
5 7
1 5 1
2 5 1
3 5 1
4 5 1
1 2 2
2 3 2
3 4 2
5
1 5
5 1
2 5
1 5
1 4
1
1
1
1
2
Let's consider the first sample.
The figure above shows the first sample.
- Vertex 1 and vertex 2 are connected by color 1 and 2.
- Vertex 3 and vertex 4 are connected by color 3.
- Vertex 1 and vertex 4 are not connected by any single color.
题意:给你一个图n个点,m条边;
每条边有个颜色,每次u,v只能走一条颜色的路径;
求有多少条路;
思路:暴力dfs;
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pi (4*atan(1.0))
#define eps 1e-14http://v.ifeng.com/program/lyyy/
const int N=2e5+,M=1e6+,inf=1e9+,MOD=;
const ll INF=1e18+;
struct edge
{
int v,w;
int nex;
}edge[N];
int head[N],edg;
void init()
{
memset(head,-,sizeof(head));
edg=;
}
void add(int u,int v,int w)
{
++edg;
edge[edg].v=v;
edge[edg].w=w;
edge[edg].nex=head[u];
head[u]=edg;
}
int now,to,ans;
int flag[N];
int hh[N];
void dfs(int u,int pre)
{
//cout<<u<<" "<<pre<<endl;
if(u==to)
{
if(!hh[pre]&&pre!=-)
{
ans++; hh[pre]=;
}
return;
}
for(int i=head[u];i!=-;i=edge[i].nex)
{
int v=edge[i].v;
if(flag[v])continue;
int w=edge[i].w;
if(pre==-||w==pre)
{
flag[v]=;
dfs(v,w);
flag[v]=;
}
}
}
int main()
{
init();
int n,m;
scanf("%d%d",&n,&m);
for(int i=;i<m;i++)
{
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
add(u,v,w);
add(v,u,w);
}
int q;
scanf("%d",&q);
while(q--)
{
memset(hh,,sizeof(hh));
ans=;
scanf("%d%d",&now,&to);
flag[now]=;
dfs(now,-);
flag[now]=;
printf("%d\n",ans);
}
return ;
}
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