Problem 11(Largest product in a grid)

Problem 11(Largest product in a grid)

In the 20×20 grid below, four numbers along a diagonal line have been marked in red.

08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

The product of these numbers is 26 × 63 × 78 × 14 = 1788696.

What is the greatest product of four adjacent numbers in the same direction (up, down, left, right, or diagonally) in the 20×20 grid?

In Python:

#PE11 Largest product in a grid
f = open("./PE11_number.txt", 'r')
data=[int(num) for num in f.read().split()]
f.close()

import time

mult = 1
mults = []
start_time = time.time()

#Horizontal
for i in range(0, 397):
    if i % 20 < 17:
        mult = 1
        for j in range(0, 4):
            mult *= data[i + j]
        mults.append(mult)

# Verticle
for i in range(0, 340):
    mult = 1
    for j in range(0, 4):
        mult *= data[i + 20 * j]
    mults.append(mult)

# Diagonal
for i in range(0, 337):
    if i % 20 < 17:
        mult = 1
        for j in range(0, 4):
            mult = mult * data[i + 21 * j]
        mults.append(mult)

# Antidiagonal
for i in range(0, 340):
    if i % 20 > 2:
        mult = 1
        for j in range(0, 4):
            mult *= data[i + 19 * j]
        mults.append(mult)

print(max(mults))
print(time.time()-start_time, "seconds")

Run time: 0.0018842220306396484 seconds

In Java:

//Euler11 Largest product in a grid

package project_euler;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Collections;

public class Euler11 {

public static void main(String[] args) throws IOException {

long startTime = System.currentTimeMillis();

int mult = 1;

String[] data;

ArrayList<Integer> dataList = new ArrayList<Integer>();

ArrayList<Integer> mults = new ArrayList<Integer>();

BufferedReader br = new BufferedReader (new FileReader("./Euler11_number.txt"));

while (true) {

String line = br.readLine();

if (line == null) break;

data = line.split(" ");

for (int i = 0; i < data.length; i++)

{

dataList.add(Integer.parseInt(data[i]));

}

}

br.close();

//Horisontal

for (int i = 0; i < 397; i++) {

if (i % 20 < 17) {

mult = 1;

for (int j = 0; j < 4; j++) {

mult *= dataList.get(i + j);

}

mults.add(mult);

}

}

//Verticle

for (int i = 0; i < 340; i++) {

mult = 1;

for (int j = 0; j < 4; j++) {

mult *= dataList.get(i + 20 * j);

}

mults.add(mult);

}

//Diagonal

for (int i = 0; i < 337; i++) {

if (i % 20 < 17) {

mult = 1;

for (int j = 0; j < 4; j++) {

mult *= dataList.get(i + 21 * j);

}

mults.add(mult);

}

}

//Antidiagonal

for (int i = 0; i < 340; i++) {

if (i % 20 > 2) {

mult = 1;

for (int j = 0; j < 4; j++) {

mult *= dataList.get(i + 19 * j);

}

mults.add(mult);

}

}

Collections.sort(mults);

System.out.println(mults.get(mults.size()-1));

long endTime = System.currentTimeMillis();

System.out.println((double)(endTime - startTime)/(double)1000 + "seconds");

}

}

Run Time: 0.012seconds

Solution: 70600674

[from Project Euler: https://projecteuler.net/problem=11]