Problem Link: http://oj.leetcode.com/problems/path-sum-ii/ The basic idea here is same to that of Path Sum. However, since the problem is asking for all possible root-to-leaf paths, so we should use BFS but not DFS. The python code is as follows. # D…

Problem Link: http://oj.leetcode.com/problems/path-sum/ One solution is to BFS the tree from the root, and for each leaf we check if the path sum equals to the given sum value. The code is as follows. # Definition for a binary tree node # class TreeN…

Problem Link: http://oj.leetcode.com/problems/word-ladder-ii/ Basically, this problem is same to Word Ladder I, which uses a double-direction BFS. However, the difference is that we need to keep track of all paths during the double-direction BFS in o…

Problem link: http://oj.leetcode.com/problems/word-break-ii/ This problem is some extension of the word break problem, so the solution is based on the discussion in Word Break. We also use DP to solve the problem. In this solution, A[i] is not a bool…

Problem Link: http://oj.leetcode.com/problems/palindrome-partitioning-ii/ We solve this problem by using Dynamic Programming. Optimal Sub-structure Assume a string S has the palindrome minimum cuts n, and S = W1 + W2 + ... + Wn where Wi is a palindro…

Problem link: http://oj.leetcode.com/problems/single-number-ii/ The problem seems like the Single Number. Suppose we have following (3m+1) numbers in the array A: x0, x1, x1, x1, ..., xm, xm, xm We are asked to find out the value of x0. However we ca…

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 相比较判断一个树中是否有sum为某一值的…

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 求路径的和与某一特定的值时候对等即可,简…

问题描述:给出一个升序排列好的整数数组,找出2个数,它们的和等于目标数.返回这两个数的下标(从1开始),其中第1个下标比第2个下标小. Input: numbers={2, 7, 11, 15}, target=9Output: index1=1, index2=2 分析:在排序好的数组中进行查找,很容易想到用二分查找的思想.这里相当于是二分查找两个数,可以把最小值和最大值作为起点求和(sum). 若sum<target,则需要把较小元素也就是low处元素变大,此时不能直接把mid赋值给low,…

题目:Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note th…