fal.cpp

#include<iostream>
using namespace std;
int firstocc(int arr[],int n,int key){
  int s = 0,e = n-1;
  int mid = s +(e-s)/2;
  int ans = -1;
  while (s<=e) {

  if(arr[mid]==key){
    ans =  mid;
    e = mid-1;
  }
  else if (key>arr[mid]) {
    s = mid+1;
    }
    else if(key<arr[mid]){
      e = mid-1;
    }
    mid = s + (e-s)/2;
}
return ans;
}

int lastocc(int arr[],int n,int key){
  int s = 0,e = n-1;
  int mid = s +(e-s)/2;
  int ans = -1;
  while (s<=e) {

  if(arr[mid]==key){
    ans =  mid;
    s = mid+1;
  }
  else if (key>arr[mid]) {
    s = mid+1;
    }
    else if(key<arr[mid]){
      e = mid-1;
    }
    mid = s + (e-s)/2;
}
return ans;
}
int main(){
  int arr[11]={1,2,3,3,3,3,3,4,5,6,7};
  cout<<"First Occurance is at index "<<firstocc(arr,11,3)<<endl;
  cout<<"Last  Occurance is at index "<<lastocc(arr,11,3)<<endl;

  return 0;
}