Some interesting modules in cpp

1dpeak.cpp

// 1d peak finding problem in lecture 1
// peak referred to local maximum
// there will be multiple local maximum, we need to find atleast one

#include<bits/stdc++.h>
using namespace std;
int peak(int arr[],int start,int end,int n){
	int mid = start + (end-start)/2;
	
	//checking mid index elemenet as peak by comparing with neighbours if the neighbours exist
	if((mid==0 || arr[mid-1]<=arr[mid]) && (mid==n-1||arr[mid+1]<=arr[mid] ))
		return mid;
	else if(mid>0 && arr[mid-1]>arr[mid])
		return peak(arr,start,mid-1,n);
	else return peak(arr,mid+1,end,n);
}
int main(){
	int n;
	cout<<"Enter the numer of elements\t";
	while(1){
		cin>>n;
		if(cin.good()){
			break;
		}
		if(cin.fail()){
			cin.clear();
			cin.ignore();
			cout<<"Enter a valid input\t";
		}
	}
	cout<<"Enter array elements"<<endl;
	int arr[n];
	for(int i=0;i<n;i++){
		cin>>arr[i];
	}
	cout<<"The peak is ";
	cout<<arr[peak(arr,0,n-1,n)]<<endl;
	return 0;
}