Codeforces Round #306 (Div. 2) D. Regular Bridge

题意：http://mp.weixin.QQ.com/s/ZKQI6_9XpsPRycHwzTu5Sw

题解：http://mp.weixin.qq.com/s/nHw70ZSuh_FvWNRgOhH6Xw

补充：构图可以参考Havel定理，暴力简单~

#include<bits/stdc++.h>using namespace std;int main() {  int k, deg[101];  cin >> k;  if (k % 2 == 0) {    puts("NO");  } else if (k == 1) {    puts("YES/n2 1/n1 2");  } else {    int n = (k + 2) * 2;    int m = n * k / 2;    printf("YES/n%d %d/n", n, m);    int u0 = 1, u1 = n / 2;    int cnt = (m - 1) / 2;    int u, v, i = 1;    fill(deg + 1, deg + 1 + n / 2, k);    deg[n / 2]--;    bool flag = true;    while (i <= cnt) {      if (flag) {        u = u0++;        v = u0;        while (deg[u]--) {          printf("%d %d/n", u, v);          printf("%d %d/n", u + n / 2, v + n / 2);          deg[v++]--;          i++;        }      } else {        u = u1--;        v = u1;        while (deg[u]--) {          printf("%d %d/n", u, v);          printf("%d %d/n", u + n / 2, v + n / 2);          deg[v--]--;          i++;        }      }      flag = !flag;    }    printf("%d %d/n", n / 2, n);  }  return 0;}