Recursion error for a algorithmic problem-CodePudding

I was trying to do the question- First negative integer in every windows of size k from a array (b) of size n. I tried using recursion but the below error came. I am trying to figure out but didn't get my mistake. Please look into the code below

ans = []
def fnc(b,n,k):
    global ans
    dq = []
    
    for i in range(0,k):
        if b[i]<0:
            dq.append(b[i])
    if len(dq) != 0:
        ans.append(dq[0])
    else:
        ans.append(0)
        
    dq = []
    b.remove(b[0])
    bnew = b
    nnew = len(bnew)  # or nnew = n-1
    
    while len(bnew) > 1:
        fnc(bnew,nnew,k)

input:
B = [12, -1, -7, 8, -15, 30, 16, 28]
N = 8
K = 3
fnc( B, N, K)
print(ans)

Showing error List Index out of range

CodePudding user response：

The problem is that you are recursively removing the first element of B, so in the run you will encounter the state where len(b) < k, so I would recommend to change the while loop to :

while len(bnew) > k:
   fnc(bnew,nnew,k)