面试题 20: 顺时针打印矩阵

一. 题目

输入一个矩阵,按照从外到里以顺时针的顺序依次打印出每一个数字.

代码请到我的代码库中下载 Point2Offer

二. 代码

package week_4;
/**难度系数:***
 * 剑指offer: 顺时针打印矩阵
 * 方法: 找规律
 * 测试用例:数组只有一行,一列,一行一列,二行二列,多行多列,为空
 * @author dingding
 * Date:2017-7-8 14:10
 * Declaration: All Rights Reserved!
 */
public class No20 {

    public static void main(String[] args) {
        test1();
        test2();
        test3();
        test4();
        test5();
    }

    //solution
    private static void printMatrixClockwisely(int[][] numbers,int columns,int rows){
        if (numbers == null || columns<=0 || rows <=0) {
            return;
        }
        int start = 0;
        while (columns >start*2 && rows >start*2){
            printMatrixInCircle(numbers,columns,rows,start);
            ++start;
        }
    }

    //顺时针打印
    private static void printMatrixInCircle(int[][] numbers, int columns, int rows, int start) {
        int endX = columns - 1 -start;  //列
        int endY = rows - 1 -start;     //行

        //从左到右打印一行
        for(int i=start;i<=endX;++i){
            int number = numbers[start][i];
            System.out.print(" "+number);
        }

        //从上到下打印一列
        if (start<endY) {
            for (int i = start+1;i<=endY;++i){
                int number = numbers[i][endX];
                System.out.print(" "+number);
            }
        }

        //从右到左打印一行
        if (start<endX && start<endY) {
            for (int i=endX-1;i>=start;--i){
                int number = numbers[endY][i];
                System.out.print(" "+number);
            }
        }

        //从下到上打印一列
        if (start < endX && start < endY-1) {
            for (int i=endY-1;i>=start+1;--i){
                int number = numbers[i][start];
                System.out.print(" "+number);
            }
        }
    }

    private static void test1() {
        int numbers[][]= {{1,2,3}};
        printMatrixClockwisely(numbers, numbers[0].length, numbers.length);
        System.out.println();
        System.out.println("================test1===================");
    }

    private static void test2() {
        int numbers[][]= {{1},{2}};
        printMatrixClockwisely(numbers, numbers[0].length, numbers.length); 
        System.out.println();
        System.out.println("================test2===================");
    }

    private static void test3() {
        int numbers[][]= {{1,2,3,4},{1,2,3,4},{1,2,3,4},{1,2,3,4}};
        printMatrixClockwisely(numbers, numbers[0].length, numbers.length); 
        System.out.println();
        System.out.println("================test3===================");
    }

    private static void test4() {
        int numbers[][]= {{1}};
        printMatrixClockwisely(numbers, numbers[0].length, numbers.length); 
        System.out.println();
        System.out.println("================test4===================");
    }

    private static void test5() {
        int numbers[][]= {{1,2,3,4,5},{6,7,8,9,10},{11,12,13,14,15}};
        printMatrixClockwisely(numbers, numbers[0].length, numbers.length); 
    }

}

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有不妥当之处,麻烦告知:D