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Find the number of index triplets i, j, k…[ftc]

Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target.

Input : 
arr[] = {-2, 0, 1, 3}
target = 2.

Output : 
2

Explanation :  Below are triplets with sum less than 2
               (-2, 0, 1) and (-2, 0, 3)    
def countrip(arr, n, sum):
    temp=0
    for i in range( 0 ,n-2):
        for j in range( i+1 ,n-1):
            for k in range( j+1, n):
                if (arr[i] + arr[j] + arr[k] < sum):
                    temp+=1
    return temp

arr= list(map(int,input('Arr : ').split(' ')))
n = len(arr)
sum = int(input('Target : '))
print(countrip(arr, n, sum))

Input_1:
Arr : -2 0 1 3
Target : 2

Output:
2


Input_2:
Arr : 5 1 3 4 7
Target : 4
Output:
0



Input_3:
Arr : 5 1 3 4 7
Target : 12

Output:
4


Input_4:
Arr : 1 3 4
Target : 5

Output:
0


Input_5:
Arr : 1 4 0 3
Target : 5

Output:
1


Illustration

Executed using python3 linux