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原创算法概论第八章部分习题解答

8.3 吝啬SAT问题是这样的：给定一组子句（每个子句都是其中文字的析取）和整数k，求一个最多有k各变量为true的满足赋值 —— 如果该赋值存在。证明吝啬SAT是NP完全问题。1.证明吝啬SAT是NP问题。2.证明吝啬SAT是NP完全问题。解：1.若存在一组对应于吝啬SAT问题子句变量的值，将这组值代入该问题中，可以在多项式时间内验证问题的解是否为真。因此吝啬SA

2017-07-14 16:19:51 584

原创 Counting Bits

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.Example:For num

2017-06-19 18:18:38 219

原创 Find Largest Value in Each Tree Row

You need to find the largest value in each row of a binary tree.Example:Input: 1 / \ 3 2 / \ \ 5 3 9 Output: [1, 3, 9]Solution

2017-06-19 18:16:55 208

原创 Binary Search Tree Iterator

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling next() will return the next smallest number in the BST.Note: next()

2017-06-19 18:13:48 201

原创 Linked List Random Node

Given a singly linked list, return a random node's value from the linked list. Each node must have thesame probability of being chosen.Follow up:What if the linked list is extremely large an

2017-06-19 17:44:03 258

原创 Subarray Sum Equals K

Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals tok.Example 1:Input:nums = [1,1,1], k = 2Output: 2Note:

2017-06-19 17:38:22 259

原创 Minimum Factorization

Given a positive integer a, find the smallest positive integer b whose multiplication of each digit equals to a. If there is no answer or the answer is not fit in 32-bit signed integer, then r

2017-06-19 17:35:42 376

原创 Minimum Height Trees

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called

2017-06-19 17:31:07 208

原创 Evaluate Division

Equations are given in the format A / B = k, where A andB are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the ans

2017-06-19 17:22:10 213

原创 Assign Cookies

Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a

2017-06-12 09:16:00 201

原创 Range Sum Query - Mutable

Given an integer array nums, find the sum of the elements between indicesi and j (i ≤ j), inclusive.The update(i, val) function modifies nums by updating the element at indexi to val.Examp

2017-06-12 09:10:31 153

原创 Find Bottom Left Tree Value

Given a binary tree, find the leftmost value in the last row of the tree.Example 1:Input: 2 / \ 1 3Output:1Example 2: Input: 1 / \ 2 3

2017-06-12 08:57:20 167

原创 Merge Two Binary Trees

Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not.You need to merge them into a new binary

2017-06-12 08:47:20 255

原创 Delete Node in a Linked List

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with val

2017-06-12 08:42:07 167

原创 Reverse Linked List

Reverse a singly linked list.Solution:/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {}

2017-06-12 08:39:59 147

原创 Minimum Absolute Difference in BST

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.Example: Input: 1 \ 3 / 2Output:1Explanatio

2017-06-12 08:29:21 188

原创 Intersection of Two Arrays

Given two arrays, write a function to compute their intersection.Example:Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return[2]. Note:Each element in the result must be unique.The res

2017-06-12 08:22:32 171

原创 Majority Element

Given an array of size n, find the majority element. The majority element is the element that appearsmore than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element

2017-03-16 22:30:42 165

原创 Kth Largest Element in an Array

Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.For example,Given [3,2,1,5,6,4] and k = 2, return

2017-03-13 13:04:13 170

原创 Two Sum

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, and you may not use the

2017-03-07 00:09:24 163

原创 Reverse Integer

Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321 Note:The input is assumed to be a 32-bit signed integer. Your function shouldreturn 0 when the r

2017-03-06 23:13:06 152

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