leetcode Archives - Page 19 of 21

Perfect Squares

Nov

26

2015

Title: Perfect Squares Source: leetcode.com Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. For example, given n = 12, return 3 because 12 = 4 + 4 + 4; given n = 13, return 2 because 13 = 4 ...

Number of Islands

Nov

26

2015

Title: Number of Islands Source: leetcode.com Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. Example 1: 11110 ...

Number of Digit One

Nov

26

2015

Title: Number of Digit One Source: leetcode.com Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n. For example: Given n = 13, Return 6, because digit 1 occurred in the following numbers: 1, 10, 11, 12, 13. Hints: Beware of overflow. Java ...

N-Queens

Nov

26

2015

Title: N-Queens Source: leetcode.com The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. image source: leetcode.com Given an integer n, return all distinct solutions to the n-queens puzzle. Each solution contains a distinct board configuration of the n-queens’ placement, where 'Q' and ...

Move Zeroes

Nov

26

2015

Title: Move Zeroes Source: leetcode.com Given an array nums, write a function to move all 0‘s to the end of it while maintaining the relative order of the non-zero elements. For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0]. Note: You must ...

Missing Number

Nov

26

2015

Title: Missing Number Source: leetcode.com Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array. For example, Given nums = [0, 1, 3] return 2. Note: Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra ...

Minimum Size Subarray Sum

Nov

26

2015

Title: Minimum Size Subarray Sum Source: leetcode.com Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn’t one, return 0 instead. For example, given the array [2,3,1,2,4,3] and s = 7, the subarray [4,3] has the minimal ...

Minimum Path Sum

Nov

26

2015

Title: Minimum Path Sum Source: leetcode.com Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. Java solution Java /* https://leetcode.com/problems/minimum-path-sum/ */ ...

Merge Intervals

Nov

26

2015

Title: Merge Intervals Source: leetcode.com Given a collection of intervals, merge all overlapping intervals. For example, Given [1,3],[2,6],[8,10],[15,18], return [1,6],[8,10],[15,18]. Java solution Java /* https://leetcode.com/problems/merge-intervals/ */ import java.util.List; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.Stack; public class MergeIntervals { public List<Interval> merge(List<Interval> intervals) { this.sort(intervals); Stack<Interval> stack = new Stack<>(); for(Interval interval : intervals) ...

Maximum Subarray

Nov

26

2015

Title: Maximum Subarray Source: leetcode.com Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4], the contiguous subarray [4,−1,2,1] has the largest sum = 6. More practice: If you have figured out the O(n) solution, try coding another solution using the divide ...