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Leetcode: First Missing Positive

时间:2014-06-27 22:24:34      阅读:346      评论:0      收藏:0      [点我收藏+]

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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.

Analysis: 第一次写的时候没有考虑到数组元素有可能重合的问题

 1 public class Solution {
 2     public int firstMissingPositive(int[] A) {
 3         int shouldbe = 1;
 4         int store = 0;
 5         java.util.Arrays.sort(A);
 6         for (int elem : A) {
 7             if (elem > 0) {
 8                 if (elem == store) continue;
 9                 else if (elem == shouldbe) {
10                     shouldbe++;
11                     store = elem;
12                 }
13                 else break;
14             }
15         }
16         return shouldbe;
17     }
18 }

 

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Leetcode: First Missing Positive

标签:style   blog   java   color   os   问题   

原文地址:http://www.cnblogs.com/EdwardLiu/p/3811206.html

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