Find number from given list for which value of the function is closest to A

Given a function F(n) = P – (0.006 * n), where P is given. Given a list of integers and a number, A. The task is to find the number from the given list for which the value of the function is closest to A.


Input : P = 12, A = 5
        List = {1000, 2000} 
Output : 1
Explanation :
Given, P=12, A=5
For 1000, F(1000) is 12 - 1000×0.006 = 6
For 2000, F(2000) is 12 - 2000×0.006 = 0
As the nearest value to 5 is 6, 
so the answer is 1000.

Input : P = 21, A = -11
        List = {81234, 94124, 52141}
Output : 3

Approach: Iterate over each value in the given list and find F(n) for every value. Now, compare the absolute difference of every value of F(n) and A and the value of n, for which the absolute difference is minimum is the answer.

Below is the implementation of the above approach:






# Python program to find number from 
# given list for which value of the 
# function is closest to A
# Function to find number from 
# given list for which value of the 
# function is closest to A
def leastValue(P, A, N, a):
    # Stores the final index
    ans = -1
    # Declaring a variable to store
    # the minimum absolute difference
    tmp = float('inf')
    for i in range(N):
        # Finding F(n)
        t = P - a[i] * 0.006
        # Updating the index of the answer if
        # new absolute difference is less than tmp
        if abs(t - A) < tmp:
            tmp = abs(t - A)
            ans = i
    return a[ans]
# Driver Code
N, P, A = 2, 12, 5
a = [1000, 2000]
print(leastValue(P, A, N, a))





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Improved By : Mithun Kumar