CareerCup 150

CC 5.3

/**
 * 5.3 Given a positive integer, print the next smallest and the next largest
 * number that have the same number of 7 bits in their binary representation.
 *
 * @author Garden
 */
public class CC5_3 {

    public static void getNextBig(int n) {
        int c = n;
        int c0 = 0;
        int c1 = 0;

        while (((c & 1) == 0) && (c != 0)) {
            c0++;
            c = c >> 1;
        }

        while ((c & 1) == 1) {
            c1++;
            c = c >> 1;
        }

        if (c0 + c1 == 31 || c0 + c1 == 0) {
            return;
        }

        int p = c0 + c1;

        n = n | (1 << p);
        n = n & (~((1 << p) - 1));
        n = n | (1 << (c1 - 1)) - 1;

        System.out.println(n);
        System.out.println(Integer.toBinaryString(n));
    }

    public static void getNextSmall(int n) {
        int c = n;
        int c0 = 0;
        int c1 = 0;

        while (((c & 1) == 1) && (c != 0)) {
            c1++;
            n = n >> 1;
        }

        if (c == 0) {
            return;
        }

        while (((c & 1) == 0) && (c != 0)) {
            c0++;
            c = c >> 1;
        }

        int p = c0 + c1;
        n = n & ((~0) << (p + 1));

        int mask = (1 << (c1 + 1)) - 1;
        n = n | mask << (c0 - 1);

        System.out.println(n);
        System.out.println(Integer.toBinaryString(n));
    }

    public static void main(String[] args) {
        getNextBig(13948);
        getNextSmall(13948);
        System.out.println("initial number:" + 13948);
        System.out.println(Integer.toBinaryString(13948));
    }
}