练习

LeetCode:21. 合并两个有序链表

/**
 * Definition for singly-linked list.
 * 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 mergeTwoLists = function (l1, l2) {
    let res = new ListNode();
    let next = res;
    while (l1 || l2) {
        if (l1 && l2) {
            if (l1.val < l2.val) {
                next.next = l1;
                l1 = l1.next;
            } else {
                next.next = l2;
                l2 = l2.next;
            }
            next = next.next;
        } else {
            next.next = l1 ? l1 : l2;
            break;
        }
    }
    return res.next;
};

LeetCode:374. 猜数字大小

/** 
 * Forward declaration of guess API.
 * @param {number} num   your guess
 * @return 	            -1 if num is lower than the guess number
 *			             1 if num is higher than the guess number
 *                       otherwise return 0
 * var guess = function(num) {}
 */

/**
 * @param {number} n
 * @return {number}
 */
var guessNumber = function (n) {
    let low = 1;
    let high = n;
    while (low <= high) {
        let mid = Math.floor((low + high) / 2)
        let gue = guess(mid)
        if (gue === -1) {
            high = mid - 1;
        } else if (gue === 1) {
            low = mid + 1
        } else {
            return mid
        }
    }
    return
};