<span>第一个缺失的整数</span>

 1 /***************************************
 2 FileName FindFirstMissingNum.cpp
 3 Author : godfrey
 4 CreatedTime : 2016/5/3
 5 ****************************************/
 6 #include <iostream>
 7 #include <cstring>
 8 #include <vector>
 9 #include <algorithm>
10 #include <stdio.h>
11 #include <stdlib.h>
12 
13 using namespace std;
14 
15 int FindFirstMissingNum(int* A,int size){
16     int i = 1;
17     A --;
18     while(i<=size){
19         if(A[i] == i){
20             i++;
21         }
22         else if((A[i] < i) || (A[i] > size) || (A[i] == A[A[i]])){
23             A[i] = A[size];
24             size --;
25         }
26         else{  // if(A[i] > i)
27             swap(A[i],A[A[i]]);
28         }
29     }
30     return i;
31 }
32 int main()
33 {
34     int a[] = {3,5,1,2,-3,7,14,8};
35     int FirstMissingNum = FindFirstMissingNum(a,sizeof(a)/sizeof(int));
36     cout<<"the FirstMissingNum: ";
37     cout<<FirstMissingNum<<endl;
38     return 0;
39 }