Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(10**8)
from collections import defaultdict
inf = 10**18
N = int(input())
S = []
C = []
for i in range(N):
    s,c = input().split()
    S.append(s)
    C.append(int(c))
    
d_l = defaultdict(lambda:inf)
def left(s1):
    res = inf
    if s1==s1[::-1]:
        return 0
    if d_l[s1] != inf:
        return d_l[s1]
    for i in range(N):
        s2 = S[i][::-1]
        c = C[i]
        if s1.startswith(s2):
            res = min(res,left(s1[len(s2):])+c)
        if s2.startswith(s1):
            res = min(res,right(s2[len(s1):])+c)
    d_l[s1] = res
    return res

d_r = defaultdict(lambda:inf)
def right(s2):
    res = inf
    if s2==s2[::-1]:
        return 0
    if d_r[s2] != inf:
        return d_r[s2]
    for i in range(N):
        s1 = S[i]
        c = C[i]
        if s1.startswith(s2):
            res = min(res,left(s1[len(s2):])+c)
        if s2.startswith(s1):
            res = min(res,right(s2[len(s1):])+c)
    d_r[s2] = res
    return res

ans = inf
for i in range(N):
    ans = min(ans,left(S[i])+C[i])

if ans == inf:
    ans = -1

print(ans)


Fixed submission:
def main(R,C,K,V):
    dp = [0]*(4*R*C)
    dp[1+4*0+4*C*0] = V[0][0]
    for k in range(4*R*C):
        n = k%4
        j = k//4%C
        i = k//(4*C)
        if n!=0:
            if i != 0 and n==1:
                dp[k] = max(dp[k-4*C-n:k-4*C-n+4])+V[i][j]
            if j != 0:
                dp[k] = max(dp[k],dp[k-4],dp[k-5]+V[i][j])
        if n==0:
            if i != 0:
                dp[k] = max(dp[k-4*C-n:k-4*C-n+4])

    print(max(dp[-5:-1]))

if __name__ == '__main__':
    R,C,K = map(int,input().split())
    C += 1
    rcv = [list(map(int,input().split())) for _ in range(K)]
    V = [[0]*C for _ in range(R)]
    for i in range(K):
        r,c,v = rcv[i]
        r -= 1
        c -= 1
        V[r][c] = v
    main(R,C,K,V)

Buggy python submission (verdict: Time Limit Exceeded):
def main(R,C,K,V):
    dp = [[[0,0,0,0] for _ in range(C)] for _ in range(R)]
    dp[0][0][1] = V[0][0]
    for i in range(R):
        for j in range(C):
            for n in range(4):
                if n!=0:
                    if i != 0 and n==1:
                        dp[i][j][n] = max(dp[i-1][j][0],dp[i-1][j][1],dp[i-1][j][2],dp[i-1][j][3])+V[i][j]
                    if j != 0:
                        dp[i][j][n] = max(dp[i][j][n],dp[i][j-1][n],dp[i][j-1][n-1]+V[i][j])
                if n==0:
                    if i != 0:
                        dp[i][j][n] = max(dp[i-1][j][0],dp[i-1][j][1],dp[i-1][j][2],dp[i-1][j][3])

    print(max(dp[-1][-1]))

if __name__ == '__main__':
    R,C,K = map(int,input().split())
    rcv = [list(map(int,input().split())) for _ in range(K)]
    V = [[0]*C for _ in range(R)]
    for i in range(K):
        r,c,v = rcv[i]
        r -= 1
        c -= 1
        V[r][c] = v
    main(R,C,K,V)

Fixed submission:
def main(R,C,K,V):
    dp = [0]*(4*R*C)
    dp[1+4*0+4*C*0] = V[0][0]
    for k in range(4*R*C):
        n = k%4
        j = k//4%C
        i = k//(4*C)
        if n!=0:
            if i != 0 and n==1:
                dp[k] = max(dp[k-4*C-n:k-4*C-n+4])+V[i][j]
            if j != 0:
                dp[k] = max(dp[k],dp[k-4],dp[k-5]+V[i][j])
        if n==0:
            if i != 0:
                dp[k] = max(dp[k-4*C-n:k-4*C-n+4])

    print(max(dp[-5:-1]))

if __name__ == '__main__':
    R,C,K = map(int,input().split())
    C += 1
    rcv = [list(map(int,input().split())) for _ in range(K)]
    V = [[0]*C for _ in range(R)]
    for i in range(K):
        r,c,v = rcv[i]
        r -= 1
        c -= 1
        V[r][c] = v
    main(R,C,K,V)