题目: Given two binary strings, return their sum (also a binary string). For example,a = "11"b = "1"Return "100". 代码: class Solution { public: string addBinary(string a, string b) { std::string result; std::string::reverse_iter…

题目: Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 return…

题目: Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following is not: 1 / \ 2 2 \ \ 3 3 Note:Bonus points if you could solve…

题目: Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value. 代码: /** * Definition for a binary tree node. * struct TreeNode…

题意: 给出n个地雷所在位置,正好能够组成正方形的地雷就可以拿走..为了简化题目,只考虑平行于横轴的正方形.. 问最多可以拿走多少个正方形.. 思路: 先找出可以组成正方形的地雷组合cnt个.. 然后st = 1<<cnt.. 用位运算来考虑取哪一个组合可以拿走最多的地雷且满足题目条件.. Tips: 题目比较烦恼的地方是解决: ①. 所选集合里面的地雷会不会重复拿.. ②. 所选集合里面在同一个地方取走的地雷会不会比该地方题目给出的地雷数多.. 同一个地点可能有多个地雷,如果用去重就不好算多…

题意: 我们定义十进制数x的权值为f(x) = a(n)*2^(n-1)+a(n-1)*2(n-2)+...a(2)*2+a(1)*1,a(i)表示十进制数x中第i位的数字. 题目给出a,b,求出0~b有多少个不大于f(a)的数. 思路: 数位DP,用来学习数位DP了. <数位DP> 所谓数位DP就是基于考虑数字的每一位来转移的DP. 例如求比456小的数,可以这么考虑, 4          5               6   4       5             (0~6) 4…

题目: Given an array of words and a length L, format the text such that each line has exactly L characters and is fully (left and right) justified. You should pack your words in a greedy approach; that is, pack as many words as you can in each line. Pa…

题目: Divide two integers without using multiplication, division and mod operator. If it is overflow, return MAX_INT. 代码: class Solution { public: int divide(int dividend, int divisor) { ) ? INT_MAX : INT_MIN; && dividend==INT_MIN) return INT_MAX; /…

题目: Given two numbers represented as strings, return multiplication of the numbers as a string. Note: The numbers can be arbitrarily large and are non-negative. 代码: class Solution { public: string multiply(string num1, string num2) { const int n1 = n…

题目: Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n). For example,S = "ADOBECODEBANC"T = "ABC" Minimum window is "BANC". Note:If there is no such wind…