无法在数组中打印最后增加的序列

Question

I am writing an algorithm for printing increasing sequences in an array, but my current solution doesn't print only the last sequence. This is because the if conditions doesn't eval at the last index of the array. The algorithm below should output [-10, 4] [1, 120, 150] [1, 5, 7] but instead it skips the [1, 5, 7] sequence. Can someone please help me here!

public class Sequence {
    public static void main(String[] args) {
        int[] test = {1000, -10, 4, 1, 120, 150, 1, 5, 7};
        Outputpattern(test);
    }

    public static void printList(int[] arr, int l, int u) {
        System.out.println(Arrays.toString(Arrays.copyOfRange(arr, l, u)));
    }

    public static void Outputpattern(int[] arr) {
        int i = 0;
        int l = 0;
        while (i < arr.length - 1) {
            if (arr[i] > arr[i + 1]) {
                if (i != l) {
                    printList(arr, l, i + 1);
                }
                l = i + 1;
            }
            i++;
        }
    }
}

Answer 1

You only print a sequence when you find a number that is lower than the previous one. But you also need to print a sequence when you reach the end. This solution will only print the sequence at the end if it has length more than 1.

int i = 0;
int l = 0;
while (i < arr.length) {                                // I changed the bound
    if (i == arr.length - 1 || arr[i] > arr[i + 1]) {   // I added a 2nd condition
        if (i != l) {
            printList(arr, l, i + 1);
        }
        l = i + 1;
    }
    i++;
}

Answer 2

The while loop recognizes when a sequence ends and prints out that sequence. But after the loop has ended you simply need to print the last sequence.

public static void Outputpattern(int[] arr) {
    int i = 0;
    int l = 0;
    while (i < arr.length - 1) {
        ...
    }

    // the last sequence
    printList(arr, l, i + 1);
}

To generalize your question: It is about to find sublists in a list while looping over the list. You can detect sublist boundaries within the loop and flush each sublist. But in the end you also need to flush the last list.

That said there seem to be implementation issues with your current boundary detection and the variables which remember that state.

Answer 3

Take care on border conditions.

Try this:

public static void outputPattern(int[] arr) {
        int l = 0;
        for (int i = 0; i < arr.length; i++) {
            if ((i < arr.length - 1) && (arr[i] <= arr[i + 1])) continue;
            if (i != l) printList(arr, l, i + 1);
            l = i + 1;
        }
    }

And please follow java naming conventions.