From d9d22a85e09288364a9d63fbe7d7c1fc2d71819d Mon Sep 17 00:00:00 2001
From: goose <tochenyuxiao@163.com>
Date: Sat, 20 Aug 2022 23:22:16 +0800
Subject: [PATCH] feat(add): big number add;

---
 lib/add.js | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/lib/add.js b/lib/add.js
index 1714b95..bd5d924 100644
--- a/lib/add.js
+++ b/lib/add.js
@@ -1,5 +1,27 @@
-function add() {
+function add(num1, num2) {
   // 实现该函数
+  let maxLength = Math.max(num1.length, num2.length);
+  // num1和num2位数对齐，位数较小的前面补0
+  num1 = num1.padStart(maxLength, '0');
+  num2 = num2.padStart(maxLength, '0');
+  let res = '';// 存放最后得到的结果
+  let figure = 0;// figure = 两个数字对应位数数值相加 + 进位
+  let currentNum = 0;// 对应位数的结果
+  let carry = 0;// 进位
+  for (let i = num1.length - 1; i >= 0; i--) {
+    figure = parseInt(num1[i]) + parseInt(num2[i]) + carry;
+    currentNum = figure % 10;
+    carry = Math.floor(figure / 10);
+
+    res = currentNum + res;
+  }
+  // 首位进位
+  if (carry) {
+    res = carry + res
+  }
+  console.log(res);
+  return res
 }
 
+
 module.exports = add
\ No newline at end of file