Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1].T

def drop(S):
    for i in range(W):
        col = S[i]
        S[i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:-1] == S[1:])
    for i in range(1,W):
        x[i] = x[i-1] * equal[i-1] + 1
    for i in range(W-2,-1,-1):
        x[i][equal[i]] = x[i+1][equal[i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(j):
    T = S.copy()
    T[j,0] = 0
    return simulate(T,0)

answer = 0
for i in range(H):
    x = max(calc(j) for j in range(W))
    if answer < x:
        answer = x
    H -= 1
    S = S[:,1:]
print(answer)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import time
start = time.time()

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1].T

def drop(S):
    for i in range(W):
        col = S[i]
        S[i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:-1] == S[1:])
    for i in range(1,W):
        x[i] = x[i-1] * equal[i-1] + 1
    for i in range(W-2,-1,-1):
        x[i][equal[i]] = x[i+1][equal[i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(j):
    T = S.copy()
    T[j,0] = 0
    return simulate(T,0)

answer = 0
for i in range(H):
    x = max(calc(j) for j in range(W))
    if answer < x:
        answer = x
    H -= 1
    S = S[:,1:]
    if time.time() - start > 0.9:
        break
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1].T

def drop(S):
    for i in range(W):
        col = S[i]
        S[i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:-1] == S[1:])
    for i in range(1,W):
        x[i] = x[i-1] * equal[i-1] + 1
    for i in range(W-2,-1,-1):
        x[i][equal[i]] = x[i+1][equal[i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(i,j):
    T = S.copy()
    T[j,i] = 0
    return simulate(T,0)

answer = max(calc(i,j) for i in range(H) for j in range(W))
print(answer)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import time
start = time.time()

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1].T

def drop(S):
    for i in range(W):
        col = S[i]
        S[i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:-1] == S[1:])
    for i in range(1,W):
        x[i] = x[i-1] * equal[i-1] + 1
    for i in range(W-2,-1,-1):
        x[i][equal[i]] = x[i+1][equal[i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(j):
    T = S.copy()
    T[j,0] = 0
    return simulate(T,0)

answer = 0
for i in range(H):
    x = max(calc(j) for j in range(W))
    if answer < x:
        answer = x
    H -= 1
    S = S[:,1:]
    if time.time() - start > 0.9:
        break
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1]

def drop(S):
    for i in range(W):
        col = S[:,i]
        S[:,i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:,:-1] == S[:,1:])
    for i in range(1,W):
        x[:,i] = x[:,i-1] * equal[:,i-1] + 1
    for i in range(W-2,-1,-1):
        x[:,i][equal[:,i]] = x[:,i+1][equal[:,i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(i,j):
    T = S.copy()
    T[i,j] = 0
    return simulate(T,0)

answer = max(calc(i,j) for i in range(H) for j in range(W))
print(answer)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import time
start = time.time()

import numpy as np

H,W,K = map(int,readline().split())
S = np.array([list(line.rstrip()) for line in readlines()]).astype(np.int8) - ord('0')

# 下から上の順に
S = S[::-1].T

def drop(S):
    for i in range(W):
        col = S[i]
        S[i] = drop_col(col)

def drop_col(col):
    x = np.zeros(H,np.int8)
    nonzero = col[col != 0]
    x[:len(nonzero)] = nonzero
    return x

def cnt_connection(S):
    # 横につながっている個数
    x = np.ones_like(S)
    equal = (S[:-1] == S[1:])
    for i in range(1,W):
        x[i] = x[i-1] * equal[i-1] + 1
    for i in range(W-2,-1,-1):
        x[i][equal[i]] = x[i+1][equal[i]]
    return x

def simulate(S,turn):
    # 落とす -> 消去、で1セット
    drop(S)
    conn = cnt_connection(S)
    remove = (conn >= K)
    before = S.sum()
    S *= (~remove)
    after = S.sum()
    if before == after:
        # 消えなかった
        return 0
    else:
        x = simulate(S,turn+1)
        return x + ((before - after) << turn)

def calc(j):
    T = S.copy()
    T[j,0] = 0
    return simulate(T,0)

answer = 0
for i in range(H):
    x = max(calc(j) for j in range(W))
    if answer < x:
        answer = x
    H -= 1
    S = S[:,1:]
    if time.time() - start > 0.9:
        break
print(answer)