递归求全排列（dfs)

递归求全排列（dfs)

一张图看懂。

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#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <iostream>
#include <algorithm>
#include <functional>
#include <stack>
#include <ctime>
#include <cstdlib>
//#pragma comment (linker, "/STACK:256000000")
using namespace std;
#define db(x) cout<<x<<endl

typedef long long ll;
const int N = 200 + 10;
const int INF = 0x3f3f3f;

void print(int x[])
{
    for(int i = 0; i < 4; i++){
        printf("%d ", x[i]);
    }
    cout << endl;
}
void f(int x[], int k)
{
    int i, t;
    if (k >= 4)
    {
        print(x);
        return;
    }
    for (i = k; i < 4; i++)
    {
        {                  
            t = x[k];
            x[k] = x[i];
            x[i] = t;
        }
        f(x, k + 1);
        {                  
            t = x[k];
            x[k] = x[i];
            x[i] = t;
        }
    }
}
int main()
{
    int x[] = {1, 2, 3, 4};
    f(x, 0);
    return 0;
}