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    Mr. Kitayuta's Colorful Graph

    Mr. Kitayuta has just bought an undirected graph consisting of n vertices and medges. 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.

    Input

    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 — aibi (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.

    Output

    For each query, print the answer in a separate line.

    Example

    Input
    4 5
    1 2 1
    1 2 2
    2 3 1
    2 3 3
    2 4 3
    3
    1 2
    3 4
    1 4
    Output
    2
    1
    0
    Input
    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
    Output
    1
    1
    1
    1
    2

    Note

    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:有多条不同颜色的路径,求给定两点间相同颜色的路径条数。

    思路:由于数据范围不大,可以开一个二维数组,使用二维并查集来处理多个相交的连通块。f[i][j],i表示颜色,f[i][j]表示j的祖先。枚举每种color,当两点祖先相同时,即为有这种color路径使他们连通。

    #include<stdio.h>
    
    int f[105][105];
    
    int find(int c,int x)
    {
        return f[c][x]==x?x:f[c][x]=find(c,f[c][x]);
    }
    
    void join(int c,int x,int y)
    {
        int fx=find(c,f[c][x]),fy=find(c,f[c][y]);
        if(fx!=fy) f[c][fy]=fx;
    }
    
    int main()
    {
        int n,m,q,a,b,c,type,cc,i,j;
        scanf("%d%d",&n,&m);
        type=0;
        for(i=1;i<=101;i++){
            for(j=1;j<=101;j++){
                f[i][j]=j;
            }
        }
        for(i=1;i<=m;i++){
            scanf("%d%d%d",&a,&b,&c);
            if(c>type) type=c;
            join(c,a,b);
        }
        scanf("%d",&q);
        for(i=1;i<=q;i++){
            scanf("%d%d",&a,&b);
            cc=0;
            for(j=1;j<=type;j++){
                if(find(j,f[j][a])==find(j,f[j][b])) cc++;
            }
            printf("%d
    ",cc);
        }
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/yzm10/p/7346194.html
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