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

 1 #include <iostream>
 2 using namespace std;
 3 int n, m, a, b;
 4 int map[1005][1005], vis[1005];
 5 void dfs(int x){
 6     for(int i = 1; i <= n; i++) if(map[x][i] != 0){
 7         map[x][i] --;
 8         map[i][x] --;
 9         dfs(i);
 
10     }
11     cout << x << " ";
12 }
13 int main(){
14     cin >> n >> m;
15     for(int i = 0; i < m; i++){
16         cin >> a >> b;
17         map[a][b] ++, map[b][a] ++;
18         vis[a] ++, vis[b] ++;
19     }
20     int x = 1;
21     for(int i = 1
 
; i <= n; i++) if(vis[i] & 1){
22         x = i;
23         break;
24     }
25     dfs(x);
26 }

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

 1 #include <iostream>
 2 #include <string.h>
 3 using namespace std;
 4 int n, cot = 0;
 5 int map[20000][2], num[40000];
 6
 
 void dfs(int x){
 7     for(int i = 0; i < 2; i++){
 8         int xx = map[x][i];
 9         if(xx > -1){
10             map[x][i] = -1;
11             dfs(xx);
12         }
13     }
14     num[++cot] = x;
15 }
16 int main(){
17     cin >> n;
18     n = 1<<(n-1);
19     memset(map, -1, sizeof(map));
20     for(int i = 0; i < n; i++){
21         int j = (i<<1)&(n-1);
22         map[i][0] = j;
23         map[i][1] = j+1;
24     }
25     dfs(0);
26     while(--cot){
27         cout<<(num[cot]&1);
28     }
29     return 0;
30 }

只有不斷學習才能進步！

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