UVA - 459 （并查集）

链接：



http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=22649

题意就是求有多少联通的块。（一开始自己脑补成双联通 然后死也过不了样例。

这道题目的读入也是挺恶心的。

#pragma comment(linker, "/STACK:10240000,10240000")
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#define mod 4294967296
#define MAX 0x3f3f3f3f
#define lson o<<1, l, m
#define rson o<<1|1, m+1, r
#define SZ(x) ((int)ans.size())
#define MAKE make_pair
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define mem(a) memset(a, 0, sizeof(a))
const double pi = acos(-1.0);
const double eps = 1e-9;
const int N = 105;
const int M = 20005;
typedef long long ll;
using namespace std;

int n, m, T;
vector <int> G[N];
int pre[N], iscut[N], bcc[N], dfs_clock, bcc_cnt;

int dfs(int u, int fa) {
    int lowu = pre[u] = ++ dfs_clock;
    int child = 0;
    for(int i = 0; i < G[u].size(); i++) {
        int v = G[u][i];
        if(!pre[v]) {
            child++;
            int lowv = dfs(v, u);
            lowu = min(lowu, lowv);
            if(lowv >= pre[u]) {
                iscut[u] = 1;
            }
        } else if(pre[v] < pre[u] && v != fa) {
            lowu = min(lowu, pre[v]);
        }
    }
    if(fa < 0 && child == 1) iscut[u] = 0;
    return lowu;
}

void find_scc() {
    mem(pre);
    mem(iscut);
    mem(bcc);
    dfs_clock = bcc_cnt = 0;
    for(int i = 0; i < n; i++) {
        if(pre[i] == 0) dfs(i, -1);
    }
}

int f[N];
int Find(int x) {
    return f[x] == x ? x : f[x] = Find(f[x]);
}

int main()
{
    //freopen("in.txt","r",stdin);
    cin >> T; getchar();getchar();
    int ca = 1;
    while(T--) {
        string s;
        getline(cin, s);

        n = s[0]-'A'+1;
        for(int i = 0; i < n; i++) G[i].clear();

        for(int i = 0; i < n; i++) {
            f[i] = i;
        }
        while(getline(cin, s) && s != "") {
            int x = s[0]-'A';
            int y = s[1]-'A';
            int fa = Find(x);
            int fb = Find(y);
            if(fa != fb) {
                f[fa] = fb;
            }
        }
        int cnt = 0;
        for(int i = 0; i < n; i++) {
            if(f[i] == i) cnt++;
        }
        if(ca > 1) puts(""); ca++;
        cout << cnt << endl;
    }

	return 0;
}