[leetcode]41 First Missing Positive

https://oj.leetcode.com/problems/first-missing-positive/

http://blog.csdn.net/linhuanmars/article/details/20884585

Public class solution {    public int firstmissingpositive (int[]  a)  {                 //  if it can be sorted, sort after 1 to start checking                  //  If a number is 3, replace it with a third space         // i, continue to replace, Dead Loop!         //  If I-bit   values  < 0,i++                 if  (a == null  | |  a.length == 0)             return  1;                int  i = 0;        while  (I < a.length)         {            if  (A [i] <= 0 | |  a[i] > a.length)             {                 //  Invalid number we don ' t care                 A[i] = -1;                 i++;                 continue;             }                         if  (a[i] == i + 1)    & Nbsp;        {                 // Aready good                 i ++;                 continue;             }                         // No need to swap             // Avoid dead loop             //  Definition J Convenient coding             int j = A[i] - 1;             if  (A[j] == a[i])              {                 A[i] = -1;                 i ++;                 continue;            }                          // swap A[i] and A[A[i] - 1]             int t = A[i];             A[i] = A[j];             a[j] = t;        }                 // Check first -1         for  (i = 0 ; i < a.length ; i ++)          {             if  (a[i] < 0)                  return i + 1;        }         return a.length + 1;    }}

[leetcode]41 First Missing Positive