AcWing 842. 排列数字（DFS）

Posted 2022-02-11 MangataTS

题目链接

https://www.acwing.com/problem/content/description/844/

思路

回溯搜索即可

代码

#include<bits/stdc++.h>
using namespace std;
//----------------自定义部分----------------
#define ll long long
#define mod 1000000007
#define endl "\\n"
#define PII pair<int,int>

int dx[4]=0,-1,0,1,dy[4]=-1,0,1,0;

ll ksm(ll a,ll b) 
	ll ans = 1;
	for(;b;b>>=1LL) 
		if(b & 1) ans = ans * a % mod;
		a = a * a % mod;
	
	return ans;


ll lowbit(ll x)return -x & x;


const int N = 2e6+10;
//----------------自定义部分----------------
int n,m,q,a[N];
bool vis[N];

void dfs(vector<int> v)
	if(v.size() == n)
		for(int i = 0;i < n; ++i) 
			cout<<v[i]<<" \\n"[i==n-1];
		
	
	for(int i = 1;i <= n; ++i)
		if(vis[i]) continue;
		vis[i] = true;
		v.push_back(i);
		dfs(v);
		v.pop_back();
		vis[i] = false;
	


int main()

	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
	
	cin>>n;
	vector<int> v;
	dfs(v);
	return 0;