10596 - Morning Walk

/* UVa 10596 Morning Walk
 * 思路：从出发点到出发点的欧拉回路(1)连通 (2)所有点的度为偶数*/
import java.util.Arrays;
import java.util.Scanner;

class Main {
	static final int MAXN = 205;
	int[][] g = new int[MAXN][MAXN];
	int[] vis = new int[MAXN];
	int[] degree = new int[MAXN];
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		Main m = new Main();
		int n,r;
		boolean isFound = true;
		while(scanner.hasNext()) {
			isFound = true;
			n = scanner.nextInt();
			r = scanner.nextInt();
			if(r == 0) {
				System.out.println("Not Possible");
				continue;
			}
			for(int i=0; i<MAXN; i++) {
				Arrays.fill(m.g[i],0);
			}
			Arrays.fill(m.degree, 0);
			Arrays.fill(m.vis, 0);
			int u=0,v;
			for(int i=0; i<r; i++) {
				u = scanner.nextInt();
				v = scanner.nextInt();
				m.g[u][v] = m.g[v][u] = 1;
				m.degree[u]++;
				m.degree[v]++;
			}
			m.dfs(u,n);
			for(int i=0; i<n; i++) {
				if(m.vis[i] == 0 || m.degree[i]%2!=0) {
					isFound = false;
					break;
				}
			}
			if(!isFound) {
				System.out.println("Not Possible");
			} else {
				System.out.println("Possible");
			}
		}
	}
	
	private void dfs(int u, int n) {
		vis[u] = 1;
		for(int v=0; v<n; v++) {
			if(g[u][v]==1 && vis[v] == 0) 
				dfs(v,n);
		}
	}
}