UVA 10054 The Necklace

来源：互联网发布：loop细分曲面算法编辑：程序博客网时间：2024/05/21 23:31

大意略。

思路：无向图的欧拉回路，其中有重复的数据，先判连通，然后判是否有奇数度的点，然后输出欧拉回路，函数有了小变化。

void euler(int u) //有重复数据{for(int v = 1; v <= maxn; v++) if(G[u][v]){--G[u][v], --G[v][u];euler(v);printf("%d %d\n", v, u);}}void euler(int u) //无重复数据{for(int v = 1; v <= maxn; v++) if(G[u][v] && !vis[u][v]){vis[u][v] = vis[v][u] = 1;euler(v);printf("%d %d\n", u, v);}}

#include <iostream>#include <cstdlib>#include <cstdio>#include <string>#include <cstring>using namespace std;const int maxn = 51;int G[maxn][maxn];int de[maxn];int p[maxn];int vis[maxn][maxn]; void init(){memset(G, 0, sizeof(G));memset(de, 0, sizeof(de));for(int i = 1; i <= maxn; i++) p[i] = i;}void euler(int u){for(int v = 1; v <= maxn; v++) if(G[u][v]){--G[u][v], --G[v][u];euler(v);printf("%d %d\n", v, u);}}void euler(int u){for(int v = 1; v <= maxn; v++) if(G[u][v] && !vis[u][v]){vis[u][v] = vis[v][u] = 1;euler(v);printf("%d %d\n", u, v);}}int find(int x){return x == p[x]? x : p[x] = find(p[x]);}void Union(int a, int b){int x = find(a), y = find(b);if(x != y) p[x] = y;}int check() //判连通 {int count = 0;for(int i = 1; i <= maxn; i++){if(de[i] & 1) return 0;if(de[i] && p[i] == i) count++;}return count == 1;}void read_case(){init();int n;scanf("%d", &n);for(int i = 0; i < n; i++){int u, v;scanf("%d%d", &u, &v);G[u][v]++, G[v][u]++;de[u]++, de[v]++;Union(u, v);}}void solve(){read_case();if(!check()) printf("some beads may be lost\n");else{for(int i = 1; i <= maxn; i++) if(de[i]){euler(i);break;}}}int main(){int T, times = 0;scanf("%d", &T);while(T--){printf("Case #%d\n", ++times);solve();printf("\n");}return 0;}