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siso
siso

Reputation: 267

Find missing element from one array comparing from other in single for loop

Is it possible to find out one missing element from one array that is not present in other array using single for loop in Java

e.g. a1 = {2,5,1,9,3,4} , length n+1

     a2 = {2,4,1,5,3}   , length n

missing element - 9 Using only a single for loop not by collections. Is it possible??

Upvotes: 2

Views: 1425

Answers (3)

Mshnik
Mshnik

Reputation: 7032

At the most basic, if we are always talking about numbers, just sum the suckers.

int sumOne = 0;
int sumTwo = 0;

for(int i = 0; i < a1.length; i++){
    sumOne += a1[i];
    if(i < a2.length)
        sumTwo += a2[i];
}

int missingNumber = sumOne - sumTwo;

If the elements aren't always numbers... Ask for more loops.

Upvotes: 9

sujithvm
sujithvm

Reputation: 2411

Find missing element using XOR

class Main {
    public static void main(String[] args) {
        int[] a1 = { 2, 5, 1, 9, 3, 4 };
        int[] a2 = { 2, 4, 1, 5, 3 };

        int missingElement = a1[a1.length - 1];
        for (int i = 0; i < a2.length; i++) {
            missingElement = missingElement ^ a1[i] ^ a2[i];
        }

        System.out.println(missingElement);
    }
}

Upvotes: 4

user1935024
user1935024

Reputation:

sum the 2 arrays in one loop then subtract (max - min) = the missing element

Upvotes: 2

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