SeeSee SeeSee - 15 days ago 6
Java Question

how to count and print out only duplicates?

I know how to go through whole array, but I only need number of duplicate occurrences. I'm at beginners level, so just basic use of loops and arrays.

int[] array = {12, 23, -22, 0, 43, 545, -4, -55, 43, 12, 0, -999, -87};

for (int i = 0; i < array.length; i++) {
int count = 0;
for (int j = 0; j < array.length; j++) {

count++;
}
System.out.println(array[i] + "\toccurs\t" + count + "X");
}

Answer

You can do better if you use more than just loops and arrays, but a simple algorithm would be to use two nested for loops, and put an if statement inside that increments a counter when a duplicate is found.

int[] array = {12, 23, -22, 0, 43, 545, -4, -55, 43, 12, 0, -999, -87};

for (int i = 0; i < array.length - 1; i++) {
    int count = 1;
    for (int j = i + 1; j < array.length; j++) {
        if (array[i] == array[j]) {
            count++;
        }
    }
    if (count > 1) {
        System.out.println(array[i] + "\toccurs\t" + count + "times");
    }
}
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