剑指offer 面试题3 二维数组中的查找 java版答案

package OfferAnswer;
/**
 * 面试题三   
 * 二维数组的查找
 * @author lwk
 *
 */
public class Answer03 {
    public static void main(String[] args) {
        int[][] matrix = {{1,2,8,9},{2,4,9,12},{4,7,10,13},{6,8,11,15}};
        boolean bool = findNum(matrix,12);
        System.out.println(bool);
	}  
    public static boolean findNum(int[][] matrix, int num){
    	if(matrix == null || matrix.length == 0){
    		return false;
    	}
    	int row = matrix.length;
    	int column = matrix[0].length;
    	int i = 0;
    	int j = column - 1;
    	//每次与数组右上角的元素进行比较
    	while(i < row && j >= 0){
    		//若与该元素相等，返回true
    		if(num == matrix[i][j]){
    			return true;
    		}else if(num > matrix[i][j]){//若比该元素大，则在数组下半部分继续查找
    			i++;
    		}else{//若比该元素小，则在数组左半部分继续查找
    			j--;
    		}
    	}
    	return false;
    }
}