【アルゴリズム】【leetcode】2数の和、2数加算

/*
        
    1.           ，       ，    ，    。
    2.    ，       ，      （         ）
*/
function ListNode(val, next) {
     
    this.val = val === undefined ? 0 : val;
    this.next = next === undefined ? null : next;
}
var addTwoNumbers_2 = function (l1, l2) {
     
    let nums = [];
    let carry = 0;
    while (l1 != null || l2 != null || carry != 0) {
     
        let val1 = l1 ? l1.val : 0;
        let val2 = l2 ? l2.val : 0;
        let sum = val1 + val2 + carry;
        carry = Math.floor(sum / 10);
        l1 = l1 ? l1.next : null;
        l2 = l2 ? l2.next : null;
    }
    console.log(nums);
    let root = new ListNode(-1, null);
    let pointer = root;
    while (nums.length != 0) {
     
        pointer.next = new ListNode(nums.shift(), null);
        pointer = pointer.next;
    }
    return root.next;
};
var addTwoNumbers = function (l1, l2) {
     
    let tempRoot = new ListNode(0, null);
    let pointer = tempRoot;
    let carry = 0;
    while (l1 != null || l2 != null || carry != 0) {
     
        let val1 = l1.val || 0;
        let val2 = l2.val || 0;
        let sum = val1 + val2 + carry;
        carry = Math.floor(sum / 10);
        pointer.next = new ListNode(sum % 10, null);
        pointer = pointer.next;
        l1 = l1 ? l1.next : null;
        l2 = l2 ? l2.next : null;
    }
    return tempRoot.next;
};

let ln1 = new ListNode(3, null);
let ln2 = new ListNode(4, ln1);
let ln3 = new ListNode(2, ln2);

let ln4 = new ListNode(4, null);
let ln5 = new ListNode(6, ln4);
let ln6 = new ListNode(5, ln5);

// console.log(addTwoNumbers_2(ln3, ln6));
// console.log(addTwoNumbers(ln3, ln6));
//====================================================================================================

/*
        
    1.  map
    2.  ，    
    3.     
*/
var twoSum3 = function (nums, target) {
     
    for (let i = 0; i < nums.length; i++) {
     
        for (let j = 0; j < nums.length; j++) {
     
            if (i == j) continue;
            if (nums[i] + nums[j] == target) return [i, j];
        }
    }
};
var twoSum2 = function (nums, target) {
     
    nums.sort((a, b) => a - b);

    let head = 0;
    let tail = nums.length - 1;
    while (nums[head] + nums[tail] != target) {
     
        let val = nums[head] + nums[tail];
        if (val > target) tail -= 1;
        else head += 1;
    }
    return [head, tail];
};
var twoSum = function (nums, target) {
     
    let map = new Map();
    for (let i = 0; i < nums.length; i++) {
     
        /*
                ，       key，    value  。
                        map (                 ，   value    )
        */
        if (map.has(nums[i])) {
     
            return [map.get(nums[i]), i];
        } else {
     
            map.set(target - nums[i], i);
        }
    }
};
// console.log(twoSum3([2, 11, 7, 15], 9));