标签：style blog color os io 使用 ar for div
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：由于本题要求O(n)时间复杂度和常空间复杂度，所以考虑使用A辅助存储，直接将1,2,3,...k...交换到A[k-1]处。
1 class Solution { 2 public: 3 int firstMissingPositive( int A[], int n ) { 4 int i = 0; 5 while ( i < n ) { 6 if( A[i] > 0 && A[i] < n && A[A[i]-1] != A[i] ) { 7 swap( A[i], A[A[i]-1] ); 8 } else { 9 ++i; 10 } 11 } 12 for( i = 0; i < n && A[i] == i+1; ++i ) { ; } 13 return i+1; 14 } 15 };
标签：style blog color os io 使用 ar for div
原文地址：http://www.cnblogs.com/moderate-fish/p/3949992.html
