一笔画问题（dfs）

#include<bits/stdc++.h>

using namespace std;

int n, m, c;

const int N = 1e3 + 5;

int mapp[N][N], s[N], nums[N];

void dfs(int i)

{

for (int j = 1; j <= n; j++)

{

if (mapp[i][j] == 1)//找到右出点

{

mapp[i][j] = mapp[j][i] = 0;

dfs(j);

}

}

nums[++c] = i;

}

int main()

{

cin >> n >> m;

for (int i = 1; i <= m; i++)

{

int a, b;

cin >> a >> b;

mapp[a][b] = mapp[b][a] = 1;//左右都能走

s[a]++;

s[b]++;//记录出度入度

}

int flag = 1;//记录起点，当图是欧拉路径时奇数点为起点，欧拉回路则为初始起点即可

for (int i = 1; i <= n; i++)

{

if (s[i] % 2 == 1)

{

flag = i;

}

}

dfs(flag);

for (int i = 1; i <= c; i++)

{

cout << nums[i] << ' ';

}

}