SOURCE

// 编程题：大数相加
6453234253452432 + 7326362323251323;
// 整数字符串数组 数组
// 数组每一位元素进行相加+进位>10取个位，进位=1
// 数组每一位元素进行相加+进位<10取个位，进位=0
// 最后一位，仍然有进位，进位添加到结果里

function bigNumberSum(str1, str2) {
  const arr1 = str1.split("").reverse();
  const arr2 = str2.split("").reverse();
  const length = Math.max(arr1.length, arr2.length);
  const result = [];
  let flag = 0;
  for (let i = 0; i < length; i++) {
    const num1 = Number(arr1[i]) || 0;
    const num2 = Number(arr2[i]) || 0;
    let sum = num1 + num2 + flag;
    if (sum > +10) {
      sum = sum % 10;
      flag = 1;
    } else {
      flag = 0;
    }

    result.push(sum);
    if (i === length - 1 && flag) {
      result.push(flag);
    }
  }
  return result.reverse().join("");
}

console.log(bigNumberSum(6453234253452432,7326362323251323))