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Leetcode

yanginblackDec 4, 20151 min read

Search for a Range

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm’s runtime complexity must be in the order of O(log n).

yanginblackDec 6, 20151 min read

Permutations

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

acinomJun 9, 20152 min read

ZigZag Conversion

The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   N
A P L S I I G
Y   I   R

acinomJun 10, 20151 min read

Happy Number

Write an algorithm to determine if a number is “happy”.

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will…

DowntownGuyDec 9, 20156 min read

LeetCode — — House Robber & House Robber II

题目链接

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system…

yanginblackDec 11, 20151 min read

Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ‘ ‘, return the length of last word in the string.

If the last word does not exist, return 0.

yanginblackNov 30, 20151 min read

Implement strStr()

mplement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

yanginblackDec 5, 2015

Sudoku Solver

Write a program to solve a Sudoku puzzle by filling the empty cells.

运行时间太长了，很没效率的算法，考虑如何优化中。。。

EddieAug 18, 20151 min read

[LeetCode] Binary Tree Level Order Traversal in Objective C

Ben LiuMar 302 min read

Leetcode 238 Product of Array Except Self

Question:
Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to
the product of all the elements of nums except nums[i].
Solve it without division and in O(n).
For example, given [1,2,3,4], return [24,12,8,6].