js string sum All In One

js string sum All In One

big int number add

字符串相加 / 大数相加

"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2022-03-17
 * @modified
 *
 * @description 2. Add Two Numbers
 * @description
 * @difficulty Medium
 * @complexity O(n)
 * @time O(n)
 * @augments
 * @example
 * @link https://leetcode.com/problems/add-two-numbers/
 * @link https://leetcode-cn.com/problems/add-two-numbers/
 * @solutions
 *
 * @best_solutions
 *
 */

const log = console.log;

function sumString(a1, a2) {
  const s1 = a1.reverse();
  const s2 = a2.reverse();
  let result = [];
  let upNum = 0;
  // log('s1', s1);
  // log('s2', s2);
  if(s1.length >= s2.length) {
      result = s1;
      for (let i = 0; i < s1.length; i++) {
        let a = s1[s1.length - i - 1];
        let b = s2[s2.length - i - 1] || 0;
        // log('\na, b =',  a, b, (a + b));
        result[s1.length - i - 1] = (a + b + upNum) % 10;
        // log('result =', i, JSON.stringify(result));
        if((a + b + upNum) >= 10) {
          upNum = 1;
        } else {
          upNum = 0;
        }
        // log('upNum =',  upNum);
      }
  } else {
      result = s2;
      for (let i = 0; i < s2.length; i++) {
        let a = s2[s2.length - i - 1];
        let b = s1[s1.length - i - 1] || 0;
        result[s2.length - i - 1] = (a + b + upNum) % 10;
        if((a + b + upNum) >= 10) {
          upNum = 1;
        } else {
          upNum = 0;
        }
      }
  }
  if(upNum) {
      result.unshift(upNum);
  }
  log('result', result.reverse());
  return result.reverse();
}
sumString([9,9,9,9,9,9,9],  [9,9,9,9]);
// [8,9,9,9,0,0,0,1]

// sumString([2,4,3], [5,6,4]);
// [7,0,8]
// Explanation: 342 + 465 = 807.

// 字符串相加 / 大数相加
const addStrings = function(num1, num2) {
  let res = '';
  let temp = 0;
  const arr1 = num1.split('');
  const arr2 = num2.split('');
  while (arr1.length || arr2.length || temp) {
    // `~~` double bitwise not 双非位运算, 字符串转换成整数
    temp += ~~arr1.pop() + ~~arr2.pop();
    // 字符串相加，要注意先后顺序
    res = (temp % 10) + res;
    // 进位
    temp = temp > 9 ? 1 : 0;
  }
  // console.log('res =', res, typeof res);
  return res === "0" ? res : res.replace(/^0+/, '');
}

~~ double bitwise not 双非位运算, 字符串转换成整数

let s = `3`;
// '3'

~s;
// -4

~~s;
// 3

+s;
// 3

https://leetcode.com/problems/add-two-numbers/

solution

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */

const log = console.log; 
      
var addTwoNumbers = function(l1, l2) {
  const log = console.log;
  log(`l1`, l1)
  log(`l2`, l2)
  var carry = 0;
  var sum = 0;
  var head = new ListNode(0);
  var now = head;
  var a = l1;
  var b = l2;
  while (a !== null || b !== null) {
    sum = (a ? a.val : 0) + (b ? b.val : 0) + carry;
    carry = Math.floor(sum / 10);
    now.next = new ListNode(sum % 10);
    now = now.next;
    a = a ? a.next : null;
    b = b ? b.next : null;
  }
  if (carry) now.next = new ListNode(carry);
  log(`head`, head)
  return head.next;
};

Array.at

const arr= [1, 2, 3];

const i = 0;
console.log(arr.at(i));
// 1

const j = -1;
console.log(ar.at(j));
// 3

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at

refs

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