Buggy python submission (verdict: Runtime Error):

# coding: utf-8

# In[1]:

import sys
#input = sys.stdin.readline
N, K = map(int, input().split())
S = input()


# In[2]:

#print(N, K)
#print(len(S), S)


# In[4]:

tmp = S[0]
sums = [0]*(N+1)
counter = 1
gc = N
nb = 0
for i in range(1, N):
    if S[i] != tmp:
        sums[nb+1] = i
        nb += 1
        counter = 0
        tmp = S[i]
    else:
        gc -= 1
    counter += 1
    if i == N-1:
        sums[nb+1] = i+1

#print(N, gc)
sums = sums[:gc+1]
pl = [0]*gc
if gc < K*2:
    print(N)
else:
    if S[0] == "0":
        for i in range(-1, gc-K*2+1, 2):
            j = 0 if i < 0 else i
            pl[i] = sums[i+1+K*2]-sums[j]
    else:
        for i in range(0, gc-K*2+1, 2):
            j = i
            pl[i] = sums[i+1+K*2]-sums[j]
    print(max(pl))


# In[ ]:





Fixed submission:

# coding: utf-8

# In[5]:

import sys
#input = sys.stdin.readline
N, K = map(int, input().split())
S = input()


# In[6]:

#print(N, K)
#print(len(S), S)


# In[21]:

tmp = S[0]
sums = [0]*(N+2)
counter = 1
gc = N
nb = 0
for i in range(1, N):
    if S[i] != tmp:
        sums[nb+1] = i
        nb += 1
        counter = 0
        tmp = S[i]
    else:
        gc -= 1
    counter += 1
    if i == N-1:
        sums[nb+1] = i+1

#print(N, gc)
sums = sums[:gc+2]
#print(S)
#print(sums)
#print(gc)
#print(gc-K*2)
pl = [0]*(gc+2)
if gc < K*2:
    print(N)
else:
    if S[0] == "0":
        if S[-1] == "0":
            for i in range(-1, gc-K*2+1, 2):
                #print(i, i+1+K*2, gc)
                j = 0 if i < 0 else i
                l = gc if i+1+K*2>gc else i+1+K*2
                #print(j, l)
                pl[i] = sums[l]-sums[j]
        else:
            for i in range(-1, gc-K*2, 2):
                j = 0 if i < 0 else i
                pl[i] = sums[i+1+K*2]-sums[j]
    else:
        if S[-1] == "0":
            for i in range(0, gc-K*2+1, 2):
                #print(i, i+1+K*2, gc)
                j=i
                l = gc if i+1+K*2>gc else i+1+K*2
                #print(j, l)
                pl[i] = sums[l]-sums[j]
        else:
            for i in range(0, gc-K*2, 2):
                j = i
                pl[i] = sums[i+1+K*2]-sums[j]
    #print(pl)
    print(max(pl))


# In[ ]:

Buggy python submission (verdict: Time Limit Exceeded):

# coding: utf-8

# In[51]:

import sys
#input = sys.stdin.readline
N, K = map(int, input().split())
S = input()


# In[59]:

tmp = S[0]
f = S[0]
c_list = [0]*N
counter = 1
nb = 0
for i in range(1, N):
    #counter += 1
    #print(S[i], i)
    if S[i] != tmp:
        c_list[nb] = counter
        nb += 1
        counter = 0
        tmp = S[i]
    counter += 1
    if i == N-1:
        c_list[nb] = counter
    #print(S[i], i,counter, c_list)

#print(c_list)
pl = [0]*N
if len(c_list) <= K*2:
    #print("a")
    print(N)
else:
    #print("b")
    if f == "0":
        #print("c")
        for i in range(-1, len(c_list)-K*2, 2):
            #print(i, i+K*2+1)
            j = 0 if i < 0 else i
            pl[i] = sum(c_list[j:i+K*2+1])
    else:
        #print("d")
        for i in range(0, len(c_list)-K*2, 2):
            #print(i, i+K*2+1)
            j = i
            pl[i] = sum(c_list[j:i+K*2+1])
    #print(pl)
    print(max(pl))


# In[ ]:





Fixed submission:

# coding: utf-8

# In[5]:

import sys
#input = sys.stdin.readline
N, K = map(int, input().split())
S = input()


# In[6]:

#print(N, K)
#print(len(S), S)


# In[21]:

tmp = S[0]
sums = [0]*(N+2)
counter = 1
gc = N
nb = 0
for i in range(1, N):
    if S[i] != tmp:
        sums[nb+1] = i
        nb += 1
        counter = 0
        tmp = S[i]
    else:
        gc -= 1
    counter += 1
    if i == N-1:
        sums[nb+1] = i+1

#print(N, gc)
sums = sums[:gc+2]
#print(S)
#print(sums)
#print(gc)
#print(gc-K*2)
pl = [0]*(gc+2)
if gc < K*2:
    print(N)
else:
    if S[0] == "0":
        if S[-1] == "0":
            for i in range(-1, gc-K*2+1, 2):
                #print(i, i+1+K*2, gc)
                j = 0 if i < 0 else i
                l = gc if i+1+K*2>gc else i+1+K*2
                #print(j, l)
                pl[i] = sums[l]-sums[j]
        else:
            for i in range(-1, gc-K*2, 2):
                j = 0 if i < 0 else i
                pl[i] = sums[i+1+K*2]-sums[j]
    else:
        if S[-1] == "0":
            for i in range(0, gc-K*2+1, 2):
                #print(i, i+1+K*2, gc)
                j=i
                l = gc if i+1+K*2>gc else i+1+K*2
                #print(j, l)
                pl[i] = sums[l]-sums[j]
        else:
            for i in range(0, gc-K*2, 2):
                j = i
                pl[i] = sums[i+1+K*2]-sums[j]
    #print(pl)
    print(max(pl))


# In[ ]: