competitive-programming/solved-uva/11709.cpp at master · the-redback/competitive-programming · GitHub

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/**
 *                                   ____
 *       ____ ___  ____ ________  __/ __/
 *      / __ `__ \/ __ `/ ___/ / / / /_
 *     / / / / / / /_/ / /  / /_/ / __/
 *    /_/ /_/ /_/\__,_/_/   \__,_/_/
 *
 *    @link : https://the-redback.com
 */
#include <bits/stdc++.h>
using namespace std;

#define ppb       pop_back
#define pb(x)     push_back(x)
#define all(x)    x.begin(), x.end()
#define mem(a, b) memset(a, b, sizeof(a))
#define inf       1000000000
#define eps       1e-9
#define NN        1010

vector<int> e[NN];
vector<int> te[NN];
map<string, int> mp;
int color[NN];
vector<int> arr;

void dfs1(int u) {
    color[u] = 1;
    for (int i = 0; i < e[u].size(); i++) {
        int v = e[u][i];
        if (!color[v]) dfs1(v);
    }
    arr.pb(u);
    return;
}

void dfs2(int u, int flag) {
    color[u] = flag;
    for (int i = 0; i < te[u].size(); i++) {
        int v = te[u][i];
        if (!color[v]) dfs2(v, flag);
    }
    return;
}

int scc(int n) {
    int i;
    mem(color, 0);
    for (i = 1; i <= n; i++) {
        if (!color[i]) dfs1(i);
    }
    mem(color, 0);
    int cnt = 0;
    int r = 0;
    reverse(all(arr));
    for (i = 0; i < arr.size(); i++) {
        if (!color[arr[i]]) {
            dfs2(arr[i], ++r);
            cnt++;
        }
    }
    return cnt;
}
string s, ss;
char a[100];

int main() {
    // ios_base::sync_with_stdio(false);
    int t = 0, tc;
    int n, m, i, j, l, k;
    // cin>>tc;
    while (cin >> n >> m) {
        if (n == 0 && m == 0) return 0;
        getchar();
        int r = 1;
        for (i = 0; i < n; i++) {
            gets(a);
            s.assign(a);
            mp[s] = r++;
        }
        for (i = 0; i < m; i++) {
            gets(a);
            s.assign(a);
            gets(a);
            ss.assign(a);
            e[mp[s]].pb(mp[ss]);
            te[mp[ss]].pb(mp[s]);
        }

        int cnt = scc(n);
        printf("%d\n", cnt);
        for (i = 0; i <= n; i++) e[i].clear(), te[i].clear();
        arr.clear();
        mp.clear();
    }
    return 0;
}