摘要： First Missing Positive2014.2.8 23:43Given an unsorted integer array, find the first missing positive integer.For example,Given[1,2,0]return3,and[3,4,-1,1]return2.Your algorithm should run inO(n) time and uses constant space.Solution1: The first solution I thought of was hashing, using unordered_map. 阅读全文

摘要： Distinct Subsequences2014.2.8 22:11Given a stringSand a stringT, count the number of distinct subsequences ofTinS.A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remai 阅读全文

摘要： Container With Most Water2014.2.8 21:37Givennnon-negative integersa1,a2, ...,an, where each represents a point at coordinate (i,ai).nvertical lines are drawn such that the two endpoints of lineiis at (i,ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the conta 阅读全文

摘要： 4Sum2014.2.8 20:58Given an arraySofnintegers, are there elementsa,b,c, anddinSsuch thata+b+c+d= target? Find all unique quadruplets in the array which gives the sum of target.Note:Elements in a quadruplet (a,b,c,d) must be in non-descending order. (ie,a≤b≤c≤d)The solution set must not contain duplic 阅读全文