算法题 - 随笔分类(第8页) - Pickle

摘要：题目：大家都知道斐波那契数列，现在要求输入一个整数n，请你输出斐波那契数列的第n项。思路：经典的题目，递归的效率不如循环，因为递归要做许多重复计算。使用循环可以保存计算结果以重用。实现代码：阅读全文

posted @ 2016-03-02 19:54 Pickle 阅读(518) 评论(0) 推荐(0)

摘要：题目：把一个数组最开始的若干个元素搬到数组的末尾，我们称之为数组的旋转。输入一个非递减序列的一个旋转，输出旋转数组的最小元素。例如数组{3,4,5,1,2}为{1,2,3,4,5}的一个旋转，该数组的最小值为1。思路：首先所给的旋转数组书局部有序的，这完全可以想到使用二分查找来解决会优化线性查找的阅读全文

posted @ 2016-03-02 19:51 Pickle 阅读(810) 评论(0) 推荐(0)

使用两个栈实现队列

摘要：题目：用两个栈来实现一个队列，完成队列的Push和Pop操作。队列中的元素为int类型。思路：用两个栈来模拟队列，一个栈作为存储，另一个栈作为交换空间。队列的push操作就直接push到第一个栈中，队列的pop操作，需要取得第一个栈低的元素，所以先把第一个栈的元素出栈，入栈到第二个队列，那么取的阅读全文

posted @ 2016-03-02 19:24 Pickle 阅读(308) 评论(0) 推荐(0)

重建二叉树

摘要：题目：输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。思路：知道了二叉树的前序和中序的序列就可以使用递归的方法阅读全文

posted @ 2016-03-02 19:16 Pickle 阅读(406) 评论(0) 推荐(0)

从尾到头打印链表

摘要：题目：输入一个链表，从尾到头打印链表每个节点的值。思路：链表是不可以随机访问的，所以如果不借助辅助空间的话，每打印一个节点就会遍历一遍链表，时间复杂度为O(n^2)。那么就需要以空间换取时间，因为是倒着遍历链表，所以栈是最好的选择。只需要遍历一遍链表入栈。然后遍历栈，出栈。这样时间复杂度为O(n) 阅读全文

posted @ 2016-03-02 19:08 Pickle 阅读(247) 评论(0) 推荐(0)

替换空格

摘要：题目：请实现一个函数，将一个字符串中的空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。思路：首先要遍历字符串得到空格的数量，则替换后的字符串长度应该是原长度+空格数量*2，从新分配长度。如果从前向后替换的话，多次替换会有阅读全文

posted @ 2016-03-02 18:57 Pickle 阅读(275) 评论(0) 推荐(0)

二维数组中的查找

摘要：题目：在一个二维数组中，每一行都按照从左到右递增的顺序排序，每一列都按照从上到下递增的顺序排序。请完成一个函数，输入这样的一个二维数组和一个整数，判断数组中是否含有该整数。 array：待查找的二维数组target：查找的数字。查找到返回true，查找不到返回false。思路： 1 2 8 9 阅读全文

posted @ 2016-03-02 17:38 Pickle 阅读(405) 评论(0) 推荐(0)

LeetCode-304. Range Sum Query 2D - Immutable

摘要：Description: Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right 阅读全文

posted @ 2016-02-23 22:23 Pickle 阅读(458) 评论(0) 推荐(0)

LeetCode-Range Sum Query - Immutable

摘要：Description: Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5 阅读全文

posted @ 2016-02-22 18:24 Pickle 阅读(349) 评论(0) 推荐(0)

LeetCode-95. Unique Binary Search Trees II

摘要：Description: Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example,Given n = 3, your program shou 阅读全文

posted @ 2016-02-21 13:31 Pickle 阅读(469) 评论(0) 推荐(0)

LeetCode-96. Unique Binary Search Trees

摘要：Description: Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 阅读全文

posted @ 2016-02-21 11:55 Pickle 阅读(246) 评论(0) 推荐(0)

LeetCode-334. Increasing Triplet Subsequence

摘要：Description: Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array. Formally the function should: Re 阅读全文

posted @ 2016-02-20 19:48 Pickle 阅读(349) 评论(0) 推荐(0)

LeetCode-230. Kth Smallest Element in a BST

摘要：Description： Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note: You may assume k is always valid, 阅读全文

posted @ 2016-02-19 22:29 Pickle 阅读(418) 评论(0) 推荐(0)

LeetCode-326. Power of Three

摘要：Description: Given an integer, write a function to determine if it is a power of three. 判断一个整数是否是3的幂。基于公式log3^n可以得出y=lg(n)/log(3)如果y正好是个整数的话，说明n是3的幂。阅读全文

posted @ 2016-02-18 18:51 Pickle 阅读(295) 评论(0) 推荐(0)

LeetCode-Maximum Product of Word Lengths

摘要：Description： Given a string array words, find the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. 阅读全文

posted @ 2016-02-17 23:30 Pickle 阅读(325) 评论(0) 推荐(0)

LeetCode-328. Odd Even Linked List

摘要：Description: Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node numbe 阅读全文

posted @ 2016-02-16 19:54 Pickle 阅读(466) 评论(0) 推荐(1)

LeetCode——Gray Code

摘要：Description：The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integernrepresenting the ... 阅读全文

posted @ 2015-11-29 22:35 Pickle 阅读(196) 评论(0) 推荐(0)

LeetCode——Find the Duplicate Number

摘要：Description：Given an arraynumscontainingn+ 1 integers where each integer is between 1 andn(inclusive), prove that at least one duplicate number must e... 阅读全文

posted @ 2015-11-28 21:47 Pickle 阅读(219) 评论(0) 推荐(0)

LeetCode—— Median of Two Sorted Arrays

摘要：Description：There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time c... 阅读全文

posted @ 2015-11-10 16:06 Pickle 阅读(243) 评论(0) 推荐(0)

LeetCode——Merge k Sorted Lists

摘要：Discription：Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Subscribe to see which companies asked t... 阅读全文

posted @ 2015-11-10 15:25 Pickle 阅读(218) 评论(0) 推荐(0)

随笔分类 - 算法题

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