hdu1878判断欧拉图

来源：互联网发布：wacom绘画软件编辑：程序博客网时间：2024/06/09 19:44

/*判断是否有欧拉回路，即判断是否为欧拉图
条件1:图连通:用并查集判断
2：不含奇度顶点
*/

#include <cstdio>#include <cstring>#define N 1000using namespace std;int map[N][N];int n, m;int f[N];void init(){for (int i = 1; i <= n; i++)f[i] = i;}int find(int x){return x == f[x] ? x : f[x] = find(f[x]);}void merge(int x, int y){int t1, t2;t1 = find(x); t2 = find(y);if (t1 != t2)f[t2] = t1;else return;}int main(){while (scanf("%d", &n) != EOF && n){init();scanf("%d", &m);int t1, t2;memset(map, 0, sizeof(map));for (int i = 0; i < m; i++){scanf("%d%d", &t1, &t2);//输入有t1，t2相等的情况if (t1 == t2)continue;map[t1][t2] = map[t2][t1] = 1;merge(t1, t2);}int cnt = 0, flag1 = 0;//flag1用来标记是否连通for (int i = 1; i <= n; i++){if (f[i] == i)cnt++;}if (cnt == 1)flag1 = 1;//下边判断是否含奇度顶点int flag2 = 1;for (int i = 1; i <= n; i++){cnt = 0;for (int j = 1; j <= n; j++){if (map[i][j])cnt++;}if (cnt % 2 == 1){flag2 = 0;break;}}printf("%d\n", flag1 && flag2);}return 0;}

上边是自己的ac代码，不过觉得用图存的话比较耗时，第二部分是参考网上思路重写了一遍。

#include <cstdio>#include <cstring>#define N 1000using namespace std;int n, m;int f[N],degree[N];//记录第i点的度数void init(){for (int i = 1; i <= n; i++)f[i] = i;}int find(int x){return x == f[x] ? x : f[x] = find(f[x]);}void merge(int x, int y){int t1, t2;t1 = find(x); t2 = find(y);if (t1 != t2)f[t2] = t1;else return;}int isEuler(){for (int i = 1; i <= n; i++)if (degree[i] & 1)return 0;return 1;}int isconnect(){int cnt = 0;for (int i = 1; i <= n; i++){if (f[i] == i)cnt++;}if (cnt == 1)return 1;else return 0;}int main(){while (scanf("%d", &n) != EOF && n){init();memset(degree, 0, sizeof(degree));scanf("%d", &m);int t1, t2;for (int i = 0; i < m; i++){scanf("%d%d", &t1, &t2);//输入有t1，t2相等的情况if (t1 == t2)continue;degree[t1]++; degree[t2]++;merge(t1, t2);}printf("%d\n", isEuler() && isconnect());}return 0;}

0 0