leetcode python solution 1. two sum (easy) Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution. Example: Given nums = [2, 7, 11, 15],
Python 位操作: 按位与 &, 按位或 | 体会不到 按位异或 ^ num ^ num = 0 左移 << num << 1 == num * 2**1 右移 >> num >> 2 == num / 2**2 取反 ~ ~num == -(num + 1) 1. Single Number Given an array of integers, every element appears twice except for one. Find
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 47: Permutations IIhttps://oj.leetcode.com/problems/permutations-ii/ Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 41: First Missing Positivehttps://oj.leetcode.com/problems/first-missing-positive/ Given an unsorted integer array, find the first missing positive integer.For example,Given [1,2,0] return
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 38: Count and Sayhttps://oj.leetcode.com/problems/count-and-say/ The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ... 1 is read off as "o
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 36: Valid Sudokuhttps://oj.leetcode.com/problems/valid-sudoku/ Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where emp
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 32: Longest Valid Parentheseshttps://oj.leetcode.com/problems/longest-valid-parentheses/ Given a string containing just the characters '(' and ')',find the length of the longest valid (well
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 18: 4Sumhttps://oj.leetcode.com/problems/4sum/ Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target?Find all unique quadruplets in the arr
