Ex14.2 - Lee /w comments

/**
     * Check if matrix of integers contains a number
     * @param mat - a two-dimentional array to seach in
     * @param num - the number to seach for
     * @return true if the number is found, false otherwise
     *
     * Time Compelxity - O(logn)
     * Space Complexity - O(1)
     */
    public static boolean search(int[][] mat, int num)
    {
        // low and high values to track searching bounds
        int rL = 0, rH = mat.length;
        int cL = 0, cH = mat.length;

        // center pivot
        int pR = rL + (rH - rL)/2;
        int pC = cL + (cH - cL) / 2;


        while(mat[pR][pC] != num)
        {
            // if the lower and upper bounds are equals we are done scanning
            if(rH == rL || cH == cL)
                return false;

            // setting pivots to matrix center value
            pR = rL + (rH - rL)/2;
            pC = cL + (cH - cL) / 2;

            // checking lower left quadrant
            if(num >= mat[pR][cL])
            {
                rL = pR;
                cH = pC;
            }
            // checking lower right quadrant
            else if(num >= mat[pR][pC])
            {
                rL = pR;
                cL = pC;
            }
            // checking upper right quadrant
            else if(num >= mat[rL][pC])
            {
                rH = pR;
                cL = pC;
            }
            // checking upper left quadrant
            else
            {
                rH = pR;
                cH = pC;
            }
        }

        return true;
    }