3 Three 1's appear in the array.

Recursion

AP Computer Science A· difficulty 3/5

public static int countX(int[] a, int i, int target) {
    if (i == a.length) return 0;
    int rest = countX(a, i + 1, target);
    return (a[i] == target ? 1 : 0) + rest;
}
int[] arr = {1, 2, 1, 3, 1};
System.out.println(countX(arr, 0, 1));

What is printed?

A
$3$
check_circle
B
$2$
C
$5$
D
$1$

Explanation

Three 1's appear in the array.

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