Category: Leetcode

Leetcode 41 First Missing Positive Java Solution

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0] Output: 3 Example 2: Input: [3,4,-1,1] Output: 2 Example 3: Input: [7,8,9,11,12] Output: 1 Note: Your algorithm should run in O(n) time and uses constant extra space. Solution 1: class Solution { public int firstMissingPositive(int[] nums) { for(int i=0;i<nums.length;i++){ if(nums[i]>0 && nums[i]!=…… Continue reading Leetcode 41 First Missing Positive Java Solution

Leetcode 37 Sudoku Solver Java Solution

Write a program to solve a Sudoku puzzle by filling the empty cells. A sudoku solution must satisfy all of the following rules: Each of the digits 1-9 must occur exactly once in each row.Each of the digits 1-9 must occur exactly once in each column.Each of the the digits 1-9 must occur exactly once in each of the 9 3×3 sub-boxes of the grid. Empty cells are…… Continue reading Leetcode 37 Sudoku Solver Java Solution

Leetcode 36 Valid Sudoku Java Solution

Determine if a 9×9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules: Each row must contain the digits 1-9 without repetition.Each column must contain the digits 1-9 without repetition.Each of the 9 3×3 sub-boxes of the grid must contain the digits 1-9 without repetition. A partially filled sudoku which is valid. The Sudoku board could be partially filled, where empty…… Continue reading Leetcode 36 Valid Sudoku Java Solution

Leetcode 35 Search Insert Position Java Position

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Example 1: Input: [1,3,5,6], 5 Output: 2 Example 2: Input: [1,3,5,6], 2 Output: 1 Example 3:…… Continue reading Leetcode 35 Search Insert Position Java Position

Leetcode 33 Search in Rotated Sorted Array Java Solution

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand. (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]). You are given a target value to search. If found in the array return its index, otherwise return -1. You may assume no duplicate exists in the array. Your algorithm’s runtime complexity must be in the order of O(log n).…… Continue reading Leetcode 33 Search in Rotated Sorted Array Java Solution

Leetcode 31 Next Permutation Java Solution

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order). The replacement must be in-place and use only constant extra memory. Here are some examples. Inputs are in the left-hand column and its corresponding outputs…… Continue reading Leetcode 31 Next Permutation Java Solution

Leetcode 787 Cheapest Flights Within K Stops Java Solution

There are n cities connected by m flights. Each flight starts from city u and arrives at v with a price w. Now given all the cities and flights, together with starting city src and the destination dst, your task is to find the cheapest price from src to dst with up to k stops. If there is no…… Continue reading Leetcode 787 Cheapest Flights Within K Stops Java Solution

Leetcode 27 Remove Element Java Solution

Given an array nums and a value val, remove all instances of that value in-place and return the new length. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory. The order of elements can be changed. It doesn’t matter what you leave beyond the new length. Example 1: Given nums…… Continue reading Leetcode 27 Remove Element Java Solution

Leetcode 26 Remove Duplicates from Sorted Array Java Solution

Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory. Example 1: Given nums = [1,1,2], Your function should return length = 2, with the first two elements of nums…… Continue reading Leetcode 26 Remove Duplicates from Sorted Array Java Solution

Leetcode 24 Swap Nodes in Pairs Java Solution

Given a linked list, swap every two adjacent nodes and return its head. You may not modify the values in the list’s nodes, only nodes itself may be changed. Example: Given 1->2->3->4, you should return the list as 2->1->4->3. Solution 1: public class Solution { public ListNode swapPairs(ListNode head) { if(head == null || head.next == null) return…… Continue reading Leetcode 24 Swap Nodes in Pairs Java Solution