Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 题意: 给定了一个无序数组,要求找到第一个缺失的正整数.如1,2,4,5的第一个缺失的正整数是3.要求时…

# -*- 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…

41. First Missing Positive Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. My Thought 题目大意 给定一个数组,…

一天一道LeetCode系列 (一)题目 Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. (二)解题 /* 首先对初始vector进行排序,然后设定…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. [题目分析] 给定一个整数数组,找出数组中第一个缺失的正整数.比如[1,2,0]缺少3,[3,4,-1,…

First Missing Positive Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 解法一:O(nlogn) time and O(1) sp…

题目如下: 解题思路:这题看起来和[leetcode]448. Find All Numbers Disappeared in an Array很相似,但是有几点不同:一是本题的输入存在负数,二是没有约定输入元素的最大值.那么,怎么可以把本题转换成448题的场景呢?首先,我们可以求出输入数组nums中所有正整数的数量,记为p,那么显然能得出这个结论:1 <=answer < p+1.然后,我们可以通过交换把所有值不在这个区间内的元素值移动到数组的后半部分.记nums前半部分[0:length]…

41. First Missing Positive Problem's Link ---------------------------------------------------------------------------- Mean: 给你一组整数,找出第一个空缺的正整数. 要求:时间O(n),空间O(n). analyse: 这题时间O(n)想了半天没想到,用O(n*logn)过的. 然后看了discuss,想法非常巧妙,自愧不如. Time complexity: O(N) v…

leetcode - 41. First Missing Positive - Hard descrition Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant s…

乘风破浪:LeetCode真题_041_First Missing Positive 一.前言 这次的题目之所以说是难,其实还是在于对于某些空间和时间的限制. 二.First Missing Positive 2.1 问题 2.2 分析与解决     读了题目我们或许还不理解题意,其实是说正常的数组应该是[1,2,3,4....]这样的数组,或者打乱次序的,但是对于不是这样的数组,我们需要从中找到从那个数字开始缺少的,这个数字就是最小的数字,比如2,3,4,那么缺少的就是1.比如1,2,4,就是…

一.题目说明 题目是41. First Missing Positive,求一个未排序队列中缺失的最小正整数.时间复杂度要求是O(n).难度是Hard,确实难. 二.我的解答 不考虑时间复杂度,首先对队列进行排序,然后从第一个正数开始,如果不是1就返回1,否则继续查找2....找不到就返回,找到就继续. 代码如下: #include<iostream> #include<vector> #include<algorithm> #include<unordered_…

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0] Output: 3 Example 2: Input: [3,4,-1,1] Output: 2 Example 3: Input: [7,8,9,11,12] Output: 1 Note: Your algorithm should run in O(n) time and uses co…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 这道题求的是在一个乱序数组中缺少的第一个正数,要求时间复杂度o(n)空间复杂度为1. 先上代码 pack…

题目描述: Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 解题思路: 参考http://blog.csdn.net/nanjunxiao/articl…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 题意分析: 本题是给一个整数的数组,让你按顺序找出第一个缺失的正整数.也就是说从1开始查找,找到了1再找…

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0] Output: 3 Example 2: Input: [3,4,-1,1] Output: 2 Example 3: Input: [7,8,9,11,12] Output: 1 Note: Your algorithm should run in O(n) time and uses co…

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0]Output: 3Example 2: Input: [3,4,-1,1]Output: 2Example 3: Input: [7,8,9,11,12]Output: 1Note: Your algorithm should run in O(n) time and uses constant…

First Missing Positive  Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 思路:这个题刚開始是没有思路的,难就难在O(n)时间…

题目: Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 链接:   http://leetcode.com/problems/first-missing…

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0] Output: 3 Example 2: Input: [3,4,-1,1] Output: 2 Example 3: Input: [7,8,9,11,12] Output: 1 Note: Your algorithm should run in O(n) time and uses co…

在leetCode上做的第一个难度是hard的题,题目如下: Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 关键是要实现0(N)的时间复杂度以及常数级…

First Missing Positive Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 题目意思: 返回第一个缺失的正数. 时间复杂度应该在O(n…

Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in \(O(n)\) time and uses constant space. 若数组为[10,20,30], 则返回0+1 = 1, 因为 A[0]!=( 0 + 1 )…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. int firstMissingPositive(vector<int>& nums) { i…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 思路:n个数,可能的最大正整数是n,所以可以将这n个数作为哈希值.但是这样要有O(n)的额外空间. 解决…

Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 题意: 给定一个无序的序列,找到其中首次缺少的正数. 题目好抽象!!!lz表示这个题意看了老久才看明白!…

Given an unsorted integer array, find the smallest missing positive integer. Example 1: Input: [1,2,0] Output: 3 Example 2: Input: [3,4,-1,1] Output: 2 Example 3: Input: [7,8,9,11,12] Output: 1 Note: Your algorithm should run in O(n) time and uses co…

题目链接: https://leetcode.com/problems/first-missing-positive/?tab=Description   给出一个未排序的数组,求出第一个丢失的正数. 给出组合为int []nums = {0,1,3,-1,2,5}; 下面为按照参考代码1执行交换运算的输出结果   0 1 3 -1 2 51 0 3 -1 2 51 0 3 -1 2 51 0 3 -1 2 51 0 3 -1 2 51 2 3 -1 0 51 2 3 -1 0 51 2 3 -…

Given an unsorted integer array,find missing postive integer. For example , Given [1,2,0]return 3, and [3,4,-1,1]return 2. Your algorithm should run in O(n) time and users constant space. 分析如下: 首先,要理解题解: 如果输入是{1,2,3,5},输出是4. 如果输入是{1,2,3,4},输入是5. 如果输入…

1.问题描述 2.题解思路 本题的思路是对于数组中每个正的元素,应该将其放到数组中对应的位置,比如元素1 ,应该放在数组的第一个位置.以此类推,最后检查数组中元素值和下标不匹配的情况. 3.代码 int firstMissingPositive(vector<int>& nums) { ) ; ; i < nums.size() ; i++) { && nums[i] < nums.size() && nums[i] != nums[ num…