LintCode Longest Common Prefix

Sat, 19 Jan 2019 00:00:00 +0000

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string “”.

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Note:

All given inputs are in lowercase letters a-z.

JavaScript

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function(strs) {
 if(strs.length === 0)return ""
 let current = ""
 let prefix = ""
 let index = 0;
 let isTrue = true;
 while (strs[0][index]) { // Use first word as baseline
 current = strs[0][index]; // Use first word as baseline
 for(let i = 0; i < strs.length; i++){
 if((strs[i] || "")[index] !== current){
 isTrue = false;
 break
 }

 }
 if(isTrue){
 index ++;
 prefix = prefix + current;
 }else{
 break
 }
 }
 return prefix
};

LintCode Best Time to Buy and Sell Stock II

Sat, 12 Jan 2019 00:00:00 +0000

Given an array, its i-th element is the price of a given stock on day i.

Design an algorithm to calculate the maximum profit you can obtain. You can complete as many transactions as possible (buy and sell a stock multiple times).

Note: You cannot participate in multiple transactions simultaneously (you must sell the stock before buying again).

Example 1:

Input: [7,1,5,3,6,4]
Output: 7
Explanation: Buy on day 2 (stock price = 1) and sell on day 3 (stock price = 5), profit = 5-1 = 4.
Then buy on day 4 (stock price = 3) and sell on day 5 (stock price = 6), profit = 6-3 = 3.

Example 2:

Input: [1,2,3,4,5]
Output: 4
Explanation: Buy on day 1 (stock price = 1) and sell on day 5 (stock price = 5), profit = 5-1 = 4.
 Note that you cannot buy on day 1 and day 2 and then sell them later.
 Because this involves participating in multiple transactions simultaneously, you must sell the stock before buying again.

Example 3:

Input: [7,6,4,3,1]
Output: 0
Explanation: In this case, no transaction is completed, so maximum profit is 0.

JavaScript

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
 let n = 0;
 prices.forEach((element,index) => {
 if(element < prices[index +1]){
 n = prices[index +1] - element + n
 }
 });
 return n
}

LeetCode on Time Friend

LintCode Longest Common Prefix

Example 1:

Example 2:

JavaScript

LintCode Best Time to Buy and Sell Stock II

Example 1:

Example 2:

Example 3:

JavaScript