题意
给定两个人相互打电话,如果a打给b,b打给c,c打给a,则说a,b,c在同一电话圈中。给出n个人的m次通话,输出所有的电话圈
思路
用graph[u][v]=1表示u和v之间有打电话。在使用floyd算法计算所有的点对之间的值。graph[u][v]=1表示u,v之间有直接或者间接打电话。如果graph[u][v] = 1并且graph[v][u]=1,说明u和v是在同一个电话圈
代码如下
cpp
#include <bits/stdc++.h>
using namespace std;
const int N = 30;
#define _for(i, a, b) for(int i = (a); i < (b); i++)
#define _rep(i, a, b) for (int i = (a); i <= (b); i++)
int n, m;
int graph[N][N];
bool vis[N];
map<string, int> nameMap;
vector<string> names;
int getId(const string& name)
{
if (!nameMap.count(name))
{
int size = names.size();
nameMap[name] = size;
names.push_back(name);
}
return nameMap[name];
}
void fastio()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
}
int main()
{
fastio();
#ifndef ONLINE_JUDGE
ifstream fin("f:\\OJ\\uva_in.txt");
streambuf* back = cin.rdbuf(fin.rdbuf());
#endif
int kase = 1;
while (cin >> n >> m) {
if (n == 0 && m == 0) {
break;
}
if (kase > 1) {
cout << endl;
}
nameMap.clear();
names.clear();
memset(graph, 0, sizeof(graph));
fill(vis, vis + N, false);
_for(i, 0, m) {
string a, b;
cin >> a >> b;
int u = getId(a);
int v = getId(b);
graph[u][v] = 1;
}
_for(k, 0, n) {
_for(i, 0, n) {
_for(j, 0, n) {
graph[i][j] = graph[i][j] || (graph[i][k] && graph[k][j]);
}
}
}
cout << "Calling circles for data set " << kase << ":" << endl;
_for(u, 0, n) {
if (vis[u]) {
continue;
}
vis[u] = true;
cout << names[u];
_for(v, 0, n) {
if (!vis[v] && graph[u][v] && graph[v][u]) {
vis[v] = true;
cout << ", " << names[v];
}
}
cout << endl;
}
kase++;
}
#ifndef ONLINE_JUDGE
cin.rdbuf(back);
#endif
return 0;
}