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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  public static void main(String args[]) {
  11.         int[] a = new int[]{100, 2, 3, 1, 4, -10, 5, 10, 21, 6, 8, -2020, 2000000000, 2000000001};
  12.         System.out.println(findFirstPositiveMissingNumber(a));
  13.  
  14.         a = new int[]{2, 3, 1, 4, 6, 5, 7};
  15.         System.out.println(findFirstPositiveMissingNumber(a));
  16.     }
  17.  
  18.     static int findFirstPositiveMissingNumber(int[] a) {
  19.         int min = -1;
  20.         java.util.Set<Integer> set = new java.util.HashSet<Integer>(a.length); 
  21.  
  22.         for (int integer: a) {
  23.             set.add(integer);
  24.             if (integer > 0 && (integer < min || min == -1)) 
  25.                 min = integer;
  26.         }
  27.  
  28.         if (min < 0 || min > 1) return 1;
  29.  
  30.         int current = min;
  31.         while (set.contains(current)) current++;
  32.  
  33.         return current;
  34.     }
  35. }
Success #stdin #stdout 0.05s 2184192KB
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https://ideone.com/aSXmd7
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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