uva 10596(欧拉路)

题解：并查集判断是否连通，然后判断是否为欧拉路，是不是所有的结点度数都是偶数，注意R == 0的时候输出NOT

#include <stdio.h>
#include <string.h>
const int N = 200 + 5;

int du[N], flag, n, r, pa[N], vis[N];

void init() {
    memset(du, 0, sizeof(du));
    memset(vis, 0, sizeof(vis));
    for (int i = 0; i < n; i++)
        pa[i] = i;
    flag = 0;
}

int get_parent(int x) {
    return pa[x] == x ? x : get_parent(pa[x]);
}
void Union(int x, int y) {
    vis[x] = vis[y] = 1;
    int px = get_parent(x);
    int py = get_parent(y);
    if (px != py)
        pa[px] = pa[py];
}
void judge() {
    int num = 0;
    for (int i = 0; i < n; i++)
        if (vis[i] && pa[i] == i)
            num++;
    if (num > 1)
        flag = 1;
}
void judge1() {
    for (int i = 0; i < n; i++)
        if (vis[i] && du[i] % 2 != 0) {
            flag = 1;
            break;
        }
}
int main() {
    int v1, v2;
    while (scanf("%d %d", &n, &r) != EOF) {
        if (r == 0) {
            printf("Not Possible\n");
            continue;
        }
        init();
        while (r--) {
            scanf("%d%d", &v1, &v2);
            du[v1]++;
            du[v2]++;
            Union(v1, v2);
        }
        judge();
        if (flag)
            printf("Not Possible\n");
        else {
            judge1();
            if (flag)
                printf("Not Possible\n");
            else
                printf("Possible\n");
        }
    }
    return 0;
}