Question

I am looking to create a function in Java that will take in two arrays or lists and be able to tell if the first array (source) ‘fits into’ the second (target). The target array has values that can not be exceeded in the source array.

For example:

[ 16, 16, 16 ] will not fit into [ 13, 13, 22 ]

[ 12, 12 ]     will fit into [ 16, 16, 12 ]

[ 12, 18, 14 ] will not fit into [ 10, 18, 14 ]

[ 12, 24 ]     will fit into [ 10, 12, 24 ]

[ 10, 10, 10 ] will not fit into [ 10, 10 ]

My current attempt (IANA CS Major!) is ok for 3-element arrays, and that’s all I need to worry about for the short term, but I’m missing some logic in the inner loop that will prevent false negatives.

Gist: https://gist.github.com/1208514

private Boolean designFits(int[] max, int[] design) {

    Boolean designFits = true;

    Arrays.sort(max);
    Arrays.sort(design);
    int passCount = 0;

    if(design.length <= max.length) {

        for(int i = 0; i < max.length; i++) {

            for(int j = 0; j < design.length; j++) {

                if(max[i] <= design[j]) {

                    passCount++;

                }

            }

        }

        if(passCount == 0 || passCount > max.length) {
            designFits = false;

        }


    } else {
        designFits = false;

    }

    return designFits;

}

Answer 1

I think this achieves what you’re looking for:

private static boolean designFits(int[] source, int[] target) {

    //if source is bigger than target, it cannot fit
    if (source.length > target.length) {
       return false;
    }

    //sort the arrays
    Arrays.sort(source);
    Arrays.sort(target);

    //get the size difference between target and source
    int targetSizeDiff = target.length - source.length;

    //walk source:
    for (int i = 0; i < source.length; i++) {
       //compare source's value at index i with target's value at i + difference
       //if it's greater, source cannot fit
       if (source[i] > target[i + targetSizeDiff]) {
          return false;
       }
    }

    //at this point we know source can fit
    return true;
}

public static void main(String[] args) {

    //false
    System.out.println(designFits(new int[]{16, 16, 16}, new int[]{13, 13, 22}));

    //true
    System.out.println(designFits(new int[]{12, 12}, new int[]{16, 16, 12}));

    //false
    System.out.println(designFits(new int[]{12, 18, 14}, new int[]{10, 18, 14}));

    //true
    System.out.println(designFits(new int[]{12, 24}, new int[]{10, 12, 24}));

    //false
    System.out.println(designFits(new int[]{10, 10, 10}, new int[]{10, 10}));
}