BytePudding

Description Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Every close bracket has a corresponding open bracket of the same type. Solution class Solution{ public boolean isValid(String ..

class MyQueue { private Stack stack1; private Stack stack2; public MyQueue() { stack1 = new Stack(); stack2 = new Stack(); } //enqueue (FIFO) public void push(int x) { while(!stack1.isEmpty()){ stack2.push(stack1.pop()); } stack1.push(x); while(!stack2.isEmpty()){ stack1.push(stack2.pop()); } } //dequeue (FIFO) public int pop() { if(empty()){ return 0; }else{ return stack1.pop(); } } public int ..

Description 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: strs = ["flower","flow","flight"] Output: "fl" Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings. Solution class Solution{ public String longestCommonF..

Description Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a maximal substring consisting of non-space characters only. Example 1: Input: s = "Hello World" Output: 5 Explanation: The last word is "World" with length 5. Example 2: Input: s = " fly me to the moon " Output: 4 Explanation: The last word is "moon" with length 4. Solution c..

Description Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral, just two ones added together. 12 is written as XII, which is simply X + The number 27 is written as XXVII, which is XX + V + II. Roman numerals are usually written largest to smallest from left to right...

Description Given an array nums of size n, return the majority element. The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array. Example 1: Input: nums = [3,2,3] Output: 3 Example 2: Input: nums = [2,2,1,1,1,2,2] Output: 2 Solution Arrays.sort(nums); int result = nums[nums.length/2]; return result; Approach In ..

Description Given the head of a singly linked list, return true if it is a palindrome or false otherwise. Example1 Input : head = [1,2,2,1] Output : true Example2 Input : head = [1,2] Output : false Solution class Solution { public boolean isPalindrome(ListNode head) { ListNode slow = head, fast = head, prev, temp; while (fast != null && fast.next != null) { slow = slow.next; fast = fast.next.ne..

Description Given the head of a singly linked list and two integers left and right where left

문제를 제대로 안읽고 풀엇더니 오래걸렸다. non-decreasing order는 오름차순이라는 뜻이고 , 중복 값을 제거한 배열의 길이를 반환하는 문제이다. Description Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums. Consider the number of unique elements of nums..

지정된 배열의 요소를 삭제하는 문제이다. 배열의 인덱스만 변경해 간단하게 풀었다. Description Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val. Consider the number of elements in nums which are not equal to val be k, to get accepted, you need to do the following things: Chan..