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59 lines
1.3 KiB
59 lines
1.3 KiB
#include <bits/stdc++.h>
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using namespace std;
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const int INF = 0x3f3f3f3f;
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// 扩展知识：欧拉通路，欧拉回路
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// https://www.cnblogs.com/graytido/p/10421927.html
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// 并查集+欧拉回路
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typedef long long LL;
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const LL N = 1e3 + 7;
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const LL MOD = 1e9 + 7;
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int pre[N];
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int n, m;
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int degree[N];
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int find(int x) //查找根结点
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{
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int r = x;
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while (r != pre[r]) //寻找根结点
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r = pre[r];
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int i = x, j;
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while (pre[i] != r) //路径压缩
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{
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j = pre[i];
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pre[i] = r;
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i = j;
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}
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return r;
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}
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int main() {
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ios::sync_with_stdio(false);
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while (cin >> n && n) {
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cin >> m;
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memset(degree, 0, sizeof(degree));
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for (int i = 1; i <= n; i++)
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pre[i] = i;
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while (m--) {
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int a, b;
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cin >> a >> b;
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int fa = find(a);
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int fb = find(b);
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if (fa != fb) {
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pre[a] = b;
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degree[a]++;
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degree[b]++;
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}
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}
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int flag = 1;
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for (int i = 2; i <= n; i++) {
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if (degree[i] & 1 || pre[i] != pre[1]) {
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flag = 0;
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break;
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}
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}
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cout << flag << endl;
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}
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return 0;
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} |