H-Index II in C++

C++Server Side ProgrammingProgramming

Suppose we have an array of citations (The citations are non-negative integers) of a researcher. These numbers are sorted in non-decreasing order. We have to define a function to compute the researcher's h-index. According to the definition of h-index: "A scientist has index h if h of his/her N papers have at least h citations each, and the other N − h papers have no more than h citations each."

So if the input is like citations = [0,1,4,5,6], then the output will be 3, as it indicates that the researcher has five papers, they have got 0, 1, 4, 5, 6 citations respectively. Since the researcher has 3 papers with at least 4 citations each and the remaining two paper with no more than 4 citations each, then the h-index is 3.

To solve this, we will follow these steps −

  • ans := 0, low := 0, n := size of the array, high := n – 1

  • if size of the array = 0, then return 0

  • while low <= high −

    • mid := low + (high - low)/2

    • if A[mid] = size of array – mid, then return A[mid]

    • otherwise when A[mid] > n – mid, then high := mid – 1

    • otherwise low := mid + 1

  • return n – high – 1

Example(C++)

Let us see the following implementation to get better understanding −

 Live Demo

#include <bits/stdc++.h>
using namespace std;
class Solution {
   public:
   int hIndex(vector<int>& A) {
      int ans = 0;
      int low = 0;
      int n = A.size();
      int high = n - 1;
      if(A.size() == 0) return 0;
      while(low <= high){
         int mid = low + (high - low) / 2;
         if(A[mid] == A.size() - mid){
            return A[mid];
         }
         else if(A[mid] > (n - mid)){
            high = mid - 1;
         }
         else low = mid + 1;
      }
      return n - (high + 1);
   }
};
main(){
   Solution ob;
   vector<int> v = {0,1,4,5,7};
   cout << (ob.hIndex(v));
}

Input

[0,1,4,5,6]

Output

3
raja
Published on 02-May-2020 11:00:12
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