46. 全排列

简单递归

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int MAXN=1e6+10;

int a[10],vis[10];
int n;
vector<vector<int>> ans;

void dfs(vector<int> v) {
    if (v.size()==n) {
        ans.push_back(v);
        return ;
    }
    
    for (int i=0;i<n;i++) {
        if (!vis[i]) {
            vis[i]=1;
            v.push_back(a[i]);
            dfs(v);
            v.pop_back();
            vis[i]=0;
        }
    }
}

int main() {
    freopen("in.txt","r",stdin);

    cin>>n;
    for (int i=0;i<n;i++) {
        cin>>a[i];
    }
    dfs({});
    for (auto vc: ans) {
        for (auto x: vc) {
            cout<<x<<" ";
        }
        cout<<endl;
    }
    return 0;
}

粘贴到leetcode中

46. 全排列

class Solution {
public:
    
        
    vector<vector<int>> ans;
    int vis[10009];
    int n;
    
    vector<vector<int>> permute(vector<int>& nums) {
        memset(vis,0,sizeof(vis));
        ans.clear();
        n=nums.size();
        dfs({},nums);
        return ans;
    }
    
    void dfs(vector<int> v,vector<int>& nums) {
        if (v.size()==n) {
            ans.push_back(v);
            return ;
        }

        for (int i=0;i<n;i++) {
            if (!vis[i]) {
                vis[i]=1;
                v.push_back(nums[i]);
                dfs(v,nums);
                v.pop_back();
                vis[i]=0;
            }
        }
    }
};