hdu 3018 歐拉回路 一筆畫問題

題目鏈接

解析

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給你一張圖，你能最少幾筆畫完整張圖？
不同的連通塊，就有一個，若該連通塊是歐拉回路，就一筆畫完;則畫度數爲奇數的點的一半的筆畫，

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代碼

#include<iostream>  
#include<cstdio>  
#include<ctime>  
#include<cstring>  
#include<cstdlib>  
#include<vector> 
#include <algorithm>
const int maxn = 100000+10;
using namespace std;  
typedef long long LL;
using namespace std;
int deg[maxn];
int fa[maxn];
int Find(int x) {
    return fa[x] == x?x:fa[x]=Find(fa[x]);
}
int vis[maxn];
int odd[maxn];
vector<int>p;
int main() {
    int n, m;
    while (~scanf("%d%d", &n, &m)) {
        memset(deg, 0, sizeof(deg));
        p.clear();
        for (int i=1; i<=n; i++)
            fa[i] = i, vis[i] = 0, odd[i] = 0;
        for (int i=1; i<=m; i++) {
            int u, v;
            scanf("%d%d", &u, &v);
            deg[u]++;
            deg[v]++;
            u = Find(u);
            v = Find(v);
            if (u != v)
            fa[u] = v;
        }
        int res = 0;
        for (int i=1; i<=n; i++) {
            int f = Find(i);
            if (!vis[f]) {
                p.push_back(f);
                vis[f]=1;
            }
            if (deg[i]%2 == 1) 
                odd[f]++;
        }
        for (int i=0; i<p.size(); i++) {
            int u = p[i];
            if (deg[u] == 0)
                continue;
            if (odd[u] == 0)
                res++;
            else
                res += odd[u]/2;
        }
        printf("%d\n", res);
    }
    return 0;
}