JS数组相关几道算法面试题

前端小测-JS 算法题目(数组相关):

将数字转为整数数组:

已知数组:

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let num = 13579; // => [1,3,5,7,9];
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let num = 13579;
let convertArray = (num) => {
  return num
    .toString()
    .split("")
    .map((item) => parseInt(item));
};
console.log(convertArray(num));

实现整数反转,一定要注意参数是负数的坑

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let a = 456,
  b = -654;
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let revNum = (num) => {
  return num > 0
    ? parseInt(num.toString().split("").reverse().join(""))
    : -parseInt(num.toString().split("").reverse().join(""));
};

console.log("result", revNum(456), revNum(-654));

给定一个数组,数组[动态和]

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给你一个数组nums,数组[动态和]的计算公式为:runningSum = sum(nums[0],...nums[i])
请返回 nums 的动态和
输入:nums = [1,2,3,4]
输出:result = [1,3,6,10]

方法 1:双重循环

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const runningSum = function (nums) {
  let res = [];
  for (let i = 0; i < nums.length; i++) {
    let acc = 0;
    for (let j = 0; j <= i; j++) {
      acc += nums[j];
    }
    res.push(acc);
  }
  return res;
};

console.log("result", runningSum(nums));

方法 2:动态规划

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const runningSum2 = function (nums) {
  nums.reduce((pre, cur, index) => {
    nums[index] = pre + cur;
    return nums[index];
  });
  return nums;
};
console.log("result", runningSum2(nums));