30 天刷题计划（三）

345. 反转字符串中的元音字母

思路

双指针前后扫描

代码

const isVowel = (ch) => {
    return "aeiouAEIOU".includes(ch)
}

const swap = (arr, i, j)  => {
  const temp = arr[i];
  arr[i] = arr[j];
  arr[j] = temp;
}


function reverseVowels(s: string): string {
  const arr = Array.from(s)
  const len = arr.length

  let start = 0
  let end = len - 1

  while(start < end) {
    while(start < len && !isVowel(arr[start])) {
      start++
    }

    while(end > 0 && !isVowel(arr[end])) {
      end--
    }

    if (start < end) {
      swap(arr, start, end)
      start++
      end--
    }
  }

  return arr.join("")
};

151. 反转字符串中的单词

代码

function reverseWords(s: string): string {
  return s.trim().split(/\s+/).reverse().join(' ');
};

238. 除自身以外数组的乘积

思路

leetcode.cn/problems/pr…

代码

function productExceptSelf(nums: number[]): number[] {
  const len = nums.length
  const l = new Array(len)
  const r = new Array(len)
  const ans = new Array(len)

  l[0] = 1
  for(let i = 1; i < len; i++) {
    l[i] = nums[i - 1] * l[i - 1]
  }

  r[len - 1] = 1
  for(let i = len - 2; i >= 0; i--) {
    r[i] = nums[i + 1] * r[i + 1]
  }

  for(let i = 0; i < len; i++) {
    ans[i] = l[i] * r[i]
  }

  return ans
};

2704. 相等还是不相等

代码

type ToBeOrNotToBe = {
    toBe: (val: any) => boolean;
    notToBe: (val: any) => boolean;
};

function expect(val: any): ToBeOrNotToBe {
	
    const toBe = (v) => {
        if(val !== v) {
         throw Error("Not Equal")
        }
        return true
    }

    const notToBe = (v) => {
       if (val === v) {
         throw Error("Equal")
       }
       return true
    }


    return {
        toBe,
        notToBe
    }
};

/**
 * expect(5).toBe(5); // true
 * expect(5).notToBe(5); // throws "Equal"
 */