wenbao与欧拉回路

http://hihocoder.com/problemset/problem/1181

#include <iostream>
using namespace std;
int n, m, a, b;
int map[1005][1005], vis[1005];
void dfs(int x){
    for(int i = 1; i <= n; i++) if(map[x][i] != 0){
        map[x][i] --;
        map[i][x] --;
        dfs(i);
    }
    cout << x << " ";
}
int main(){
    cin >> n >> m;
    for(int i = 0; i < m; i++){
        cin >> a >> b;
        map[a][b] ++, map[b][a] ++;
        vis[a] ++, vis[b] ++;
    }
    int x = 1;
    for(int i = 1; i <= n; i++) if(vis[i] & 1){
        x = i;
        break;
    }
    dfs(x);
}

http://hihocoder.com/problemset/problem/1182 

#include <iostream>
#include <string.h>
using namespace std;
int n, cot = 0;
int map[20000][2], num[40000];
void dfs(int x){
    for(int i = 0; i < 2; i++){
        int xx = map[x][i];
        if(xx > -1){
            map[x][i] = -1;
            dfs(xx);
        }
    }
    num[++cot] = x;
}
int main(){
    cin >> n;
    n = 1<<(n-1);
    memset(map, -1, sizeof(map));
    for(int i = 0; i < n; i++){
        int j = (i<<1)&(n-1);
        map[i][0] = j;
        map[i][1] = j+1;
    }
    dfs(0);
    while(--cot){
        cout<<(num[cot]&1);
    }
    return 0;
}

只有不断学习才能进步！