Question

Fulcrum

def can_balance(items):

Each item in the list of items is now considered to be a physical weight, and therefore guaranteed to be a positive integer. Your task is to find and return a fulcrum position in this list so that when balanced on that position, the total torque of the items to the left of that position equals the total torque of the items to the right of that position. (The item on the fulcrum is assumed to be centered symmetrically on both sides, and therefore does not participate in the torque calculation.)

As taught in any introductory physics textbook, the torque of an item with respect to the fulcrum equals its weight times its distance from the fulcrum. If a fulcrum position exists, return that position, otherwise return -1 to indicate that the given itemscannot be balanced, at least not without rearranging them. (That one, by the way, would be an interesting but a more advanced problem normally suitable for a third year computer science course... but in Python, this algorithm could easily be built around this function by using the generator permutations in the module itertools to try out all possible permutations in an outer loop until you find one permutation that works. In fact, quite a few problems of this style can be solved with this "generate and test" approach without needing the fancy backtracking algorithms from third year and up.)

items	Expected result
[6, 1, 10, 5, 4]	2
[10, 3, 3, 2, 1]	1
[7, 3, 4, 2, 9, 7, 4]	-1
[42]	0

Answer 1

The program is written in python

def can_balance(items):
    for i in range(len(items)):
        tl=0 # to calculate the left torque
        for j in range(0,i):
            tl+=items[j]*(i-j)
        tr=0 # to calculate the right torque
        for k in range(i+1,len(items)):
            tr+=items[k]*(k-i)
        if(tr==tl): #checking if both the torques are equal
            return i
    
    return -1 # if index not found then return -1
    
l=[int(x) for x in input().split(" ")] #input the list
print(can_balance(l)) #calling the function to return the index
            

I hope the answer will help you. Please give a positive rating if the answer helps you.