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Count number of smallest elements in given range in C++
We are given an array of integers of size N. Variables L and R define a range between 1 and N. The goal is to find the number of smallest elements that lie in range L and R such that L>=1 and R<=N.
We will do this by traversing the elements that lie in range L and R and find the smallest.
Again, traverse the elements of the range L and R and increment count if any element is equal to smallest calculated in step 1.
Let’s understand with examples.
Input − arr[]= { 1,2,3,0,3,2,0,1 }, N=8, L=2, R=5
Output − Count of smallest in range − 1
Explanation −
Elements in range L(1) to R(5) are arr[1] to arr[4]. { 2,3,0,3 }. Smallest value is 0. Count of 0 is 1.
Input − arr[]= { 1,2,3,0,3,2,0,1 }, N=8, L=3, R=8
Output − Count of smallest in range − 2
Explanation −
Elements in range L(3) to R(8) are arr[2] to arr[7]. { 3,0,3,2,0,1 }. Smallest value is 0. Count of 0 is 2.
Approach used in the below program is as follows
We take an integer array arr[] initialized with random numbers.
Integers L and R represent the range inside arr[]. Count stores the count of smallest in range L and R.
Function countSmallest(int arr[],int n,int l, int r) takes an array, its length, L and R as input and returns the count of smallest in the range.
Initialize smallest=arr[l], leftmost element and initial count of smallest as 0.
Now if l<0 and r>=n then return 0, invalid range provided.
Start traversing the array from index l-1 to r-1. Update smallest if arr[i]<smallest.
Again, traverse the array from l-1 to r-1, if arr[i]==smallest, increment count.
Return count as desired result.
Inside main, display the result present in count.
Example
#include <bits/stdc++.h>
using namespace std;
// Function to find if number is prime
int countSmallest(int arr[],int n,int l, int r){
int smallest=arr[l];
int count=0;
if(l<0 && r>=n)
return 0;
for(int i=l-1;i<r;i++){
if(arr[i]<=smallest){
smallest=arr[i];
}
}
for(int i=l-1;i<r;i++){
if(arr[i]==smallest){
++count;
}
}
return count;
}
int main(){
int arr[] = { 3,2,1,1,2,3 };
int n = 6;
int L,R;
int count=0;
L=1,R=5;
count=countSmallest(arr,n,L,R);
cout<<endl<<"Count of number of smallest in given range:"<<count;
L=3,R=4;
count=countSmallest(arr,n,L,R);
cout<<endl<<"Count of number of smallest in given range:"<<count;
return 0;
}Output
If we run the above code it will generate the following output −
Count of number of smallest in given range:2 Count of number of smallest in given range:2
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