Leetcode 1365. How Many Numbers Are Smaller Than the Current Number

題目

Input: nums = [8,1,2,2,3]
Output: [4,0,1,1,3]
Explanation: 
For nums[0]=8 there exist four smaller numbers than it (1, 2, 2 and 3). 
For nums[1]=1 does not exist any smaller number than it.
For nums[2]=2 there exist one smaller number than it (1). 
For nums[3]=2 there exist one smaller number than it (1). 
For nums[4]=3 there exist three smaller numbers than it (1, 2 and 2).

解法思維

跑迴圈依序比大小

const smallerNumbersThanCurrent = nums => {
  let result = [];
  let count = 0;

  for (let i = 0; i < nums.length; i += 1) {
    let cv = nums[i];

    for (let j = 0; j < nums.length; j += 1) {
      let num = nums[j];

      if (cv > num) {
        count++
      }
    }

    result.push(count)
    count = 0;
  }

  return result;
};

先用 sort()排序由小到大，再由indexOf查找位置，回傳結果

let smallerNumbersThanCurrent = (nums) =>{
    let tp=Array.from(nums).sort((a,b)=>a-b)
    let result=nums.map(x=>tp.indexOf(x))
    return result
};