1107. Social Clusters (30) 并查集

题目地址

用vector<int>数组来记录每次输入有这个爱好的人的ID，
用map<int,int>来统计有几个集合，注意最后统计时还要进行路径压缩。

//// Created by aleafall on 16-10-3.//#include<iostream>#include<cstdio>#include<algorithm>#include<map>#include<vector>using namespace std;const int maxn = 1001;int father[maxn];vector<int> hobby[maxn];int findFather(int x) {    if (father[x] == x) return x;    else {        int F = findFather(father[x]);        father[x] = F;        return F;    }}void Union(int a, int b) {    int faA = findFather(a);    int faB = findFather(b);    if (faA != faB) father[faB] = faA;}int main() {    int n, k, h;    map<int, int> mp;    for (int i = 0; i < maxn; i++)        father[i] = i;    cin >> n;    for (int i = 1; i <= n; i++) {        scanf("%d: ", &k);        for (int j = 0; j < k; j++) {            scanf("%d", &h);            hobby[h].push_back(i);        }    }    for (int i = 1; i < maxn; i++) {        if (hobby[i].size() > 1) {            for (int j = 1; j < hobby[i].size(); j++)                Union(hobby[i][0], hobby[i][j]);        }    }    for (int i = 1; i <= n; i++) {    //注意路径压缩        int F = findFather(i);        if (mp.find(F) != mp.end()) mp[F]++;        else mp[F] = 1;    }    int cnt = 0, ans[maxn];    for (map<int, int>::iterator it = mp.begin(); it != mp.end(); it++) {        ans[cnt++] = it->second;    }    cout << cnt << endl;    sort(ans, ans + cnt);    for (int i = 0; i < cnt; i++) {        cout << ans[cnt - i - 1];        if (i < cnt - 1) cout << ' ';        else cout << endl;    }    return 0;}