C++ program to find minimum scalar of two vectors
Finding the minimum scalar product in C++
Here, in this page we will discuss the program to find the minimum scalar product in C++ programming language. We are given with two arrays and need to print the value of minimum scalar product that obtained.
Method Discussed :
- Method 1 : Without using inbuilt sort() function for sorting.
- Method 2 : Using sort() function for sorting.
Let’s discuss both methods one by one in brief,
Method 1 :
- Sort the first array in ascending order,
- Sort the second array in descending order.
- Declare a variable say product = 0.
- Run a loop from index 0 to n
- Set product += (arrr1[i]*arr2[i])
- After complete iteration print product.
Time and Space Complexity :
- Time Complexity : O(n2)
- Space Complexity : O(1)
Method 1 : Code in C++
Run
#include<bits/stdc++.h>
using namespace std;
int main(){
int arr1[] = {1, 2, 6, 3, 7};
int arr2[] = {10, 7, 45, 3, 7};
int n = sizeof(arr1)/sizeof(arr1[0]);
//Sort arr1 in ascending order
for(int i=0; i<n; i++){
for(int j=i+1; j<n; j++){ if(arr1[i]>arr1[j]){
int temp = arr1[i];
arr1[i] = arr1[j];
arr1[j] = temp;
}
}
}
//Sort arr2 in descending order
for(int i=0; i<n; i++){
for(int j=i+1; j<n; j++){
if(arr2[i]<arr2[j]){
int temp = arr2[i];
arr2[i] = arr2[j];
arr2[j] = temp;
}
}
}
int product = 0;
for(int i=0; i<n; i++)
product += arr1[i]*arr2[i];
cout<< product;
}
Output
149
Method 2 :
In this method we will use inbuilt sort function to sort the array.
- For, sorting arr1 in ascending order, use sort(arr1, arr1+n)
- For, sorting arr2 in descending order, use sort(arr2, arr2+n, greater()).
Time and Space Complexity :
- Time Complexity : O(n log(n))
- Space Complexity : O(1)
How to sort in descending order?
sort() takes a third parameter that is used to specify the order in which elements are to be sorted.We can pass the “greater()” function to sort in descending order.
This function does a comparison in a way that puts greater elements before.
Method 2 : Code in C++
#include<bits/stdc++.h>
using namespace std;
int main(){
int arr1[] = {1, 2, 6, 3, 7};
int arr2[] = {10, 7, 45, 3, 7};
int n = sizeof(arr1)/sizeof(arr1[0]);
//Sort arr1 in ascending order
sort(arr1, arr1+n);
//Sort arr2 in descending order
sort(arr2, arr2+n, greater<int>()); int product = 0;
for(int i=0; i<n; i++) product += arr1[i]*arr2[i];
cout<< product;
}Output
149
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