Time：2022-5-27

### Problem solving ideas

If you write too many numbers, add them（String addition）, you might write that

``````var addBinary = function(a, b) {
let maxLen = Math.max(a.length,b.length)
let flag = 0
let res = ''
let i = maxLen - 1
while(i >= 0) {
flag = Number(a[i]) + Number(b[i]) + flag
res =  flag % 10 + res;
flag = Math.floor(flag/10)
i--
}
res = flag == 1 ? '1' + res : res
return res
}``````

What if you change it to binary? Is that all right

### code

``````/**
* @param {string} a
* @param {string} b
* @return {string}
*/
var addBinary = function(a, b) {
let maxLen = Math.max(a.length,b.length)
let flag = 0
let res = ''
let i = maxLen - 1
while(i >= 0) {
flag = Number(a[i]) + Number(b[i]) + flag
res = flag % 2 + res;
flag = Math.floor(flag/2)
i--
}
res = flag == 1 ? '1' + res : res
return res
};``````

Careful friends have seen the clue, that is, they have made changes in remainder and carry, and the others have not moved, so I have summarized a general method of n-ary addition

``````/**
* @param {string} a
* @param {string} b
* @return {string}
*/
let maxLen = Math.max(a.length,b.length)
let flag = 0
let res = ''
let i = maxLen - 1
while(i >= 0) {
flag = Number(a[i]) + Number(b[i]) + flag
res = flag % radix + res;
i--
}
res = flag == 1 ? '1' + res : res
return res
};``````

### Another kind of string addition

``````/**
* @param {string} num1
* @param {string} num2
* @return {string}
*/
var addStrings = function(a, b) {
let l1 = a.length - 1
let l2 = b.length - 1
let flag = 0
let res = ''
while(l1 >= 0 || l2 >= 0) {
let x = l1 >=0 ? + a[l1] : 0
let y = l2 >=0 ? + b[l2] : 0
flag = x + y + flag
res = flag % 10 + res;
flag = Math.floor(flag/10)
l1--
l2--
}
res = flag == 1 ? '1' + res : res
return res
};``````

``````/**
* function ListNode(val, next) {
*     this.val = (val===undefined ? 0 : val)
*     this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} l1
* @param {ListNode} l2
* @return {ListNode}
*/
var addTwoNumbers = function(l1, l2) {
let dummy = new ListNode()
let cur = dummy;
let flag = 0
while(l1 || l2) {
let n1 = l1 && l1.val || 0
let n2 = l2 && l2.val || 0
let total = n1 + n2 + flag
cur.next = new ListNode(total % 10)
cur = cur.next
l1 = l1 && l1.next
l2 = l2 && l2.next
flag = Math.floor(total / 10)
}
if (flag) {
cur.next = new ListNode(flag)
}
return dummy.next
};``````

## Vue2 technology finishing 3 – Advanced chapter – update completed

3. Advanced chapter preface Links to basic chapters:https://www.cnblogs.com/xiegongzi/p/15782921.html Link to component development:https://www.cnblogs.com/xiegongzi/p/15823605.html 3.1. Custom events of components 3.1.1. Binding custom events There are two implementation methods here: one is to use v-on with vuecomponent\$ Emit implementation [PS: this method is a little similar to passing from child to parent]; The other is to use ref […]