Help With Python?

[toml_12953]

I'm trying to convert the following ANSI BASIC program to Python. The BASIC program works but the Python program gets a bad index error after some time. I've looked at it and looked at it but I can't discover what's causing the problem. Can anyone help?

BASIC Program:

Code:

100 LET T0=TIME
110 LET Y=30000
120 DIM List1(30000)
130 LET L=0
140 FOR N=1 TO 999999
150    LET M=N
160    LET C=0
170    DO WHILE M<>1
180       IF FP(M/2)=0 THEN
190          LET M=M/2
200       ELSE
210          LET M=3*M+1
220       END IF
230       LET C=C+1
240       IF M<=Y THEN
250          IF List1(M)<>0 THEN
260             LET C=C+List1(M)
270             LET M=1
280          END IF
290       END IF
300    LOOP
310    IF N<=Y THEN
320       IF List1(N)=0 THEN
330          LET List1(N)=C
340       END IF
350    END IF
360    IF C>L THEN 
370       LET L=C
380       PRINT N
390       PRINT C
400    END IF
410 NEXT N
420 PRINT TIME-T0;"seconds"
430 END

Python Program:

Code:

from time import *

def Euler14():

    t0=monotonic()

    Y = 30000
    List1 = [0] * Y
    L = 0
    for N in range(1,1000000):
        M = N
        C = 0
        while M != 1:
            if M % 2 == 0:
                M = int(M / 2)
            else:
                M = 3 * M + 1
            C = C + 1
            if M <= Y:
                if List1[M] != 0:
                    C = C + List1[M]
                    M = 1
        if N <= Y:
            if List1[N] == 0:
                List1[N] = C
        if C > L:
            L = C
            print(N)
            print(C)
        
    print(monotonic()-t0,"seconds")

[ldesnogu]

I’m not very familiar with Python but I guess list has 30000 elements indexed from 0 to 29999. So either you should dimension it to Y+1 or make comparisons <Y rather than <=Y.

Just guessing

[pascal_meheut]

Another alternative to ldesnogu approach is to use an AI to convert the code.
This gives this which seem to work. At least it runs without an error.

Code:


import time

# Initialize variables
t0 = time.time()
Y = 30000
List1 = [0] * (Y + 1)
L = 0

# Loop from 1 to 999999
for N in range(1, 1000000):
    M = N
    C = 0
    while M != 1:
        if M % 2 == 0:
            M = M // 2
        else:
            M = 3 * M + 1
        C += 1
        if M <= Y:
            if List1[M] != 0:
                C += List1[M]
                M = 1
    if N <= Y:
        if List1[N] == 0:
            List1[N] = C
    if C > L:
        L = C
        print(N)
        print(C)

print(f"{time.time() - t0} seconds")

[toml_12953]

(07-17-2024 05:52 PM)ldesnogu Wrote:  I’m not very familiar with Python but I guess list has 30000 elements indexed from 0 to 29999. So either you should dimension it to Y+1 or make comparisons <Y rather than <=Y.

Just guessing

Quite right! Thanks!