swap & complete permutation

// filename: main.cpp// title: swap & complete permutation// time: 2011/3/29#include <iostream>using std::cin;using std::cout;using std::endl;#include <cassert>void swap(int& a,int& b){assert(&a != &b);// 否则a会被置0a = a + b;b = a - b;a = a - b;}void perm(int data[],int n,int k){if( k == n){for(int i = 1; i <= n; i++){cout << data[i];}cout << endl;}else{// k_th// data[k]在原位perm(data,n,k+1);// data[k]与后面的数交换for(int j=k+1;j<=n;j++){swap(data[k],data[j]); perm(data,n,k+1); // 递归，使用k+1，不使用用k++，否则会修改k ☆swap(data[k],data[j]); // 还原，进行下一个交换}}}int main(int argc, char* argv[]){unsigned int n;cin >> n;int* data = new int[n+1];// 初始化，data[0]不使用for(int i = 1; i <= n; i++){data[i] = i;}perm(data,n,1);return 0;}