CODEWITHSUNDEEP
javaarrays
jimbo mugwug
jimbo mugwug

Reputation: 11

Return index of first unsorted element or array's size

I have this function below its intended purpose is to return the first index where data isn't sorted in ascending order. If the data is sorted, it will just return the length of the array. For example {10, 20, 90, 5, 70} would return 3 (90 > 5). If any of the data is null or invalid it just returns -1. Currently, the function is expecting 4 to be returned but it skips over the loops and returns -1 instead of 4. Any tips to help would be appreciated.

public static int Sorted(int[] data) {
    if (data == null)
        return -1;
    for (int i = 0; i < data.length - 1; i++) {
        if (data[i + 1] < data[i])
            return (i + 1);
    }
    return -1;
}

Test cases:

public void testSorted() {
    assertEquals(-1, Stage1.partSorted(null));
    assertEquals(1, Stage1.partSorted(new int[] { 90, 20, 40, 100 }));
    assertEquals(4, Stage1.partSorted(new int[] { 10, 20, 40, 100 }));
    assertEquals(3, Stage1.partSorted(new int[] { 10, 20, 90, 70 }));
    assertEquals(4, Stage1.partSorted(new int[] { 20, 20, 30, 40, 5, 70, 90, 80 }));
}

Upvotes: 1

Views: 84

Answers (4)

dani-vta
dani-vta

Reputation: 7225

Your code is not skipping the for loop. In your return statement, you're returning -1 instead of the array's length. This is why you're receiving -1 instead of 4 for your second test case { 90, 20, 40, 100 }.

Your code should look like this:

public static int Sorted(int[] data) {
    if (data == null)
        return -1;
    for (int i = 0; i < data.length - 1; i++) {
        if (data[i + 1] < data[i])
            return (i + 1);
    }
    return data.length;
}

Upvotes: 2

Robert Radzik
Robert Radzik

Reputation: 41

You are testing a sorted array. For loop finishes itself and the return within it is never called. Last return before end of the function should be return data.length;

public static int partSorted(int[] data) {
    if (data == null)
        return -1;
    for (int i = 0; i < data.length - 1; i++) {
        if (data[i + 1] < data[i])
            return (i + 1);
    }
    return data.length;
}

Upvotes: 3

Himanshu Raj
Himanshu Raj

Reputation: 51

Try this

    public static int Sorted(int[] data) {
    if (data == null)
        return -1;
    int parSorCount = 1;
    for (int i = 1; i < data.length; i++) {
        if (data[i - 1] <= data[i]) {
            parSorCount++;
        } else {
            break;
        }
    }
    if (parSorCount < 2) {
        return 1;
    } else {
        return parSorCount;
    }
}

Upvotes: 0

wolfenblut
wolfenblut

Reputation: 148

The reason is, for a sorted array, you pass the for loop without returning a value, then, you return -1 with your last statement. Therefore, just change return -1 to return data.length in your last statement,

Upvotes: 2

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