47.全排列-ii.js

/*
 * @lc app=leetcode.cn id=47 lang=javascript
 *
 * [47] 全排列 II
 */

// @lc code=start
/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var swap = function(nums, i, j) {
  if (i === j)
      return;
  const t = nums[i];
  nums[i] = nums[j];
  nums[j] = t;
};

var cal = function (nums, first, result) {
  if (nums.length === first) {
      result.push([...nums]);
      return;
  }

  const map = new Map();
  for (let i = first; i < nums.length; i++) {
      if (!map.get(nums[i])) {
          map.set(nums[i], true);
          swap(nums, first, i);
          cal(nums, first + 1, result);
          swap(nums, first, i);
      }
  }
};

/**
* @param {number[]} nums
* @return {number[][]}
*/
var permuteUnique = function(nums) {
  if (nums == null)
      return;
  
  nums.sort((a, b) => a - b);
  const res = [];
  cal(nums, 0, res);
  return res; 
};
s
// @lc code=end