DFS/并查集 Codeforces Round #286 (Div. 2) B - Mr. Kitayuta's Colorful Graph

 

题目传送门

 1 /*  2  题意：两点之间有不同颜色的线连通，问两点间单一颜色连通的路径有几条  3  DFS：暴力每个颜色，以u走到v为结束标志，累加条数  4  注意：无向图  5 */  6 #include <cstdio>  7 #include <iostream>  8 #include <algorithm>  9 #include <cstring> 10 #include <string> 11 #include <vector> 12 using namespace std; 13 14 const int MAXN = 1e2 + 10; 15 const int INF = 0x3f3f3f3f; 16 int n, m; 17 bool vis[MAXN]; 18 vector<pair<int, int> > V[MAXN]; 19 20 bool DFS(int u, int v, int c) 21 { 22 vis[u] = true; 23 if (u == v) return true; 24 for (int i=0; i<V[u].size (); ++i) 25  { 26 pair<int, int> p = V[u][i]; 27 if (p.second == c && !vis[p.first]) 28  { 29 if (DFS (p.first, v, c)) return true; 30  } 31  } 32 33 return false; 34 } 35 36 int main(void) //Codeforces Round #286 (Div. 2) B - Mr. Kitayuta's Colorful Graph 37 { 38 //freopen ("B.in", "r", stdin); 39 40 while (scanf ("%d%d", &n, &m) == 2) 41  { 42 for (int i=1; i<=m; ++i) 43  { 44 int u, v, c; 45 scanf ("%d%d%d", &u, &v, &c); 46  V[u].push_back (make_pair (v, c)); 47  V[v].push_back (make_pair (u, c)); 48  } 49 int q; scanf ("%d", &q); 50 while (q--) 51  { 52 int u, v; scanf ("%d%d", &u, &v); 53 int ans = 0; 54 for (int i=1; i<=m; ++i) 55  { 56 memset (vis, false, sizeof (vis)); 57 if (DFS (u, v, i)) ans++; 58  } 59 printf ("%d\n", ans); 60  } 61  } 62 63 return 0; 64 }

 1 /*  2  并查集：开在结构体的并查集，进行如下的两个操作  3  uf[c].Union (u, v); uf[i].same (u, v)  4 */  5 #include <cstdio>  6 #include <iostream>  7 #include <algorithm>  8 #include <cstring>  9 #include <vector> 10 using namespace std; 11 12 const int MAXN = 1e2 + 10; 13 const int INF = 0x3f3f3f3f; 14 struct UF 15 { 16 int rt[MAXN]; 17 void init(void) {memset (rt, -1, sizeof (rt));} 18 19 int Find(int x) {return (rt[x] == -1) ? x : rt[x] = Find (rt[x]);} 20 21 void Union(int x, int y) 22  { 23 int tx = Find (x); 24 int ty = Find (y); 25 if (tx > ty) rt[ty] = tx; 26 else if (tx < ty) rt[tx] = ty; 27  } 28 29 bool same(int x, int y) 30  { 31 return (Find (x) == Find (y)); 32  } 33 }uf[MAXN]; 34 int n, m; 35 36 int main(void) //Codeforces Round #286 (Div. 2) B - Mr. Kitayuta's Colorful Graph 37 { 38 //freopen ("B.in", "r", stdin); 39 40 while (scanf ("%d%d", &n, &m) == 2) 41  { 42 for (int i=1; i<=m; ++i) uf[i].init (); 43 for (int i=1; i<=m; ++i) 44  { 45 int u, v, c; 46 scanf ("%d%d%d", &u, &v, &c); 47  uf[c].Union (u, v); 48  } 49 int q; scanf ("%d", &q); 50 while (q--) 51  { 52 int u, v; scanf ("%d%d", &u, &v); 53 int ans = 0; 54 for (int i=1; i<=m; ++i) 55  { 56 if (uf[i].same (u, v)) ans++; 57  } 58 printf ("%d\n", ans); 59  } 60  } 61 62 return 0; 63 }

并查集