var permute = function (nums) {
  if (nums.length === 0) {
    return [];
  }
  var result = [];
  var temp = [];
  DFS(nums, 0, result, temp);
  return result;
};

function copy(array) {
  var result = [];
  for (var i = 0, len = array.length; i < len; i  ) {
    result.push(array[i]);
  }
  return result;
}

function DFS(nums, level, result, temp) {
  if (temp.length === nums.length) {
    result.push(copy(temp));
  };
  for (var i = 0; i < nums.length; i   ) {
    if (temp.indexOf(nums[i]) < 0) {
      temp.push(nums[i]);
      DFS(nums, i, result, temp);
      temp.pop(nums[i]);
    }
  }
}