Project Euler : Largest Product Of Five Consequtive Digits

The problem was that given a 1000 digit number, we had to find the largest product of 5 consecutive digits.

This was a no brainer actually. It was simple to the point question. I realized that if a 0 appeared, then the product would be minimum. So I split the given number at 0′s and stored them in an array, Each number of the array was the largest block without any 0. Now if the length of a block is less than 5, we can just avoid that block.

The whole thing now boils down to finding the largest product in blocks of length greater than 5. A simple loop completed the solution. Here is the solution as coded by me:

public class Problem_8 {
    public int getMaxProductOfFiveConsequtiveDigits(String[] nums) {
        int maxProduct = 0;

        Stopwatch stopwatch = new Stopwatch();
        stopwatch.start();

        for (String num : nums) {
            int length = num.length();
            if (length < 5)
                continue;
            int[] n = new int[5];
            for (int i = 0; i < 5; i++)
                n[i] = num.charAt(i) - '0';
            int cycle = 5;
            while (cycle < length) {
                int prod = n[0] * n[1] * n[2] * n[3] * n[4];
                if (prod > maxProduct)
                    maxProduct = prod;
                n[cycle % 5] = num.charAt(cycle) - '0';
                cycle++;
            }
        }
        stopwatch.stop();
        System.out.println("The reading for operation is: " + stopwatch);

        return maxProduct;
    }

    public static void main(String[] args) {
        String[] nums = ("73167176531330624919225119674426574742355349194934"
                + "96983520312774506326239578318016984801869478851843"
                + "85861560789112949495459501737958331952853208805511"
                + "12540698747158523863050715693290963295227443043557"
                + "66896648950445244523161731856403098711121722383113"
                + "62229893423380308135336276614282806444486645238749"
                + "30358907296290491560440772390713810515859307960866"
                + "70172427121883998797908792274921901699720888093776"
                + "65727333001053367881220235421809751254540594752243"
                + "52584907711670556013604839586446706324415722155397"
                + "53697817977846174064955149290862569321978468622482"
                + "83972241375657056057490261407972968652414535100474"
                + "82166370484403199890008895243450658541227588666881"
                + "16427171479924442928230863465674813919123162824586"
                + "17866458359124566529476545682848912883142607690042"
                + "24219022671055626321111109370544217506941658960408"
                + "07198403850962455444362981230987879927244284909188"
                + "84580156166097919133875499200524063689912560717606"
                + "05886116467109405077541002256983155200055935729725"
                + "71636269561882670428252483600823257530420752963450").split("0");
        System.out.println((new Problem_8()).getMaxProductOfFiveConsequtiveDigits(nums));
    }
}

Popularity: 6% [?]

Related posts:

1. Project Euler : Palindrome Made From Product Of Three Digit Numbers
2. Project Euler : Sum Of Digits In a^b
3. Project Euler : Greatest Product of 4 Numbers In A 20×20 Grid
4. Project Euler : Fast Factorial Computation
5. Project Euler : Numbers That Are Fifth Powers Of Their Digits