linux-hw/8/function.cpp

#include <algorithm>
#include <vector>

#include "function.h"

using namespace std;

bool isswap(vector<int> &arr, size_t beg, size_t end) {
  for (size_t i = beg; i < end; ++i) {
    if (arr[i] == arr[end])
      return false;
  }
  return true;
}

void permutation(vector<int> &arr, size_t pos, size_t len, vector<vector<int>> &res){
  if (pos == len) {
    res.push_back(arr);
    return;
  }
  for (size_t i = pos; i <= len; ++i) {
    if (isswap(arr, pos, i) == true) {
      swap(arr[pos], arr[i]);
      permutation(arr. pos + 1, len, res);
      swap(arr[pos], arr[i]);
    }
  }
}