Find the first positive integer .

closes #712

Author: Mayuri-cell

Arrays/Missing_integer.cpp

@@ -0,0 +1,79 @@
+/* Title : User will enter the unsorted array .
+      You will need to sort it and has to
+      find out the first missing positive integer from the sorted array .
+*/
+#include<iostream>
+#include<math.h>
+#include<stdlib.h>
+using namespace std;
+int main()
+{
+  int n ,j=0, i,k=1 , val;
+  cout<<" Enter the total number of elements "<<endl;
+  cin>>n;
+  int a[n];
+  cout<<" Enter the elements : \n"<<endl;
+  for(i=0;i<n;i++)
+    {  cin>>a[i]; }
+
+    for(i=0;i<n;i++)
+{    for(j=0;j<n-1;j++)
+     if(a[j]>a[j+1])
+       { val=a[j];
+         a[j]=a[j+1];
+         a[j+1]=val; }
+}
+    cout<<" Sorted array : \n"<<endl;
+    for(i=0;i<n;i++)
+    {
+      cout<<a[i]<<" ";
+    }
+    cout<<" \n"<<endl;
+    cout<<" Missing element : ";
+if(a[n-1]<=0)
+{
+   cout<<"1";
+
+}
+else {
+
+    for(i=0;i<n;i++)
+    {
+      if(a[i]>0)
+      {
+        for(j=0+i, k=1;j<=n && k<=n+1;k++,j++)
+         {
+             if(a[j]==k)
+             {
+               continue ;
+             }
+             else
+             {
+
+                 cout<<k;
+                  exit(0);
+             }  }
+       }  }
+  }}
+
+
+
+
+
+
+/*
+Enter the total number of elements
+5
+Enter the elements :
+
+12
+-43
+-5
+0
+2
+Sorted array :
+
+-43 -5 0 2 12
+
+Missing element : 1
+*/