[JAVA] Project Euler, I got stuck in Q8, so make a note

When I solved Project Euler with java, it got stuck in Q8, so I made a note.

Q8.java



public class Q8 {
  public static void main(String[] args) {
    final String STRING = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
    final int NUM =13;

    //For checking the length of the character string
    //System.out.println(STRING.length());

    int partial_product;
    int largest_product = 1;
    int position = 1;
    String digits=null;

    for(int i=0;i<=STRING.length()-NUM;i++){
    	partial_product = 1;
    	String partial_string = STRING.substring(i,i+NUM);
    	for(int t=0;t<partial_string.length	();t++){
    		partial_product *= Integer.parseInt(partial_string.substring(t,t+1));
    	}
    	if(partial_product>largest_product){
    		largest_product=partial_product;
    		digits=partial_string;
    		position=i;
    	}
    }
    System.out.println(position);
    System.out.println(digits);
    System.out.println(largest_product);
  }
}

Where you are worried

・ The algorithm should be correct, but the answer is different for some reason. -The results of the conditional clause of the if statement for updating the maximum value differ between the above and the following.

if(partial_product-largest_product>0)

~~ I will add it when it is resolved. ~~

[Addition below] As you commented, the cause was that the int type exceeded the maximum value of the type. I solved it by using a long type. Thank you very much!

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