99乘法表

　　99乘法表可以说是最基本的题目了，昨天没细看，人家要竖着打印，我搞成了横着打了。这里我横竖都贴出来纪念一下：

package com.wulinfeng.io;

public class Table99 {

    public static void main(String[] args) {
        System.out.println("横着打印：");
        print99Row();
        System.out.println("竖着打印：");
        print99Column();
        System.out.println("还是竖打，但只需一次循环：");
        print99OnceCycle();
    }

    /**
     * 横着打印99乘法表
     */
    private static void print99Row() {
        for (int i = 1; i <= 9; i++) {
            for (int j = i; j <= 9; j++) {
                System.out.printf("%d * %d = %2d	", i, j, i * j);
            }
            System.out.println("");
        }
    }

    /**
     * 竖着打印99乘法表
     */
    private static void print99Column() {
        for (int i = 1; i <= 9; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.printf("%d * %d = %2d	", j, i, i * j);
            }
            System.out.println("");
        }
    }

    /**
     * 一次循环解决问题
     */
    private static void print99OnceCycle() {
        for (int i = 1, j = 1; j <= i && i <= 9; j++) {
            System.out.printf("%d * %d = %2d	", j, i, i * j);
            if (i == j) {
                i++;
                j = 0;
                System.out.println("");
            }
        }
    }
}

　　运行结果：

横着打印：
1 * 1 =  1    1 * 2 =  2    1 * 3 =  3    1 * 4 =  4    1 * 5 =  5    1 * 6 =  6    1 * 7 =  7    1 * 8 =  8    1 * 9 =  9    
2 * 2 =  4    2 * 3 =  6    2 * 4 =  8    2 * 5 = 10    2 * 6 = 12    2 * 7 = 14    2 * 8 = 16    2 * 9 = 18    
3 * 3 =  9    3 * 4 = 12    3 * 5 = 15    3 * 6 = 18    3 * 7 = 21    3 * 8 = 24    3 * 9 = 27    
4 * 4 = 16    4 * 5 = 20    4 * 6 = 24    4 * 7 = 28    4 * 8 = 32    4 * 9 = 36    
5 * 5 = 25    5 * 6 = 30    5 * 7 = 35    5 * 8 = 40    5 * 9 = 45    
6 * 6 = 36    6 * 7 = 42    6 * 8 = 48    6 * 9 = 54    
7 * 7 = 49    7 * 8 = 56    7 * 9 = 63    
8 * 8 = 64    8 * 9 = 72    
9 * 9 = 81    
竖着打印：
1 * 1 =  1    
1 * 2 =  2    2 * 2 =  4    
1 * 3 =  3    2 * 3 =  6    3 * 3 =  9    
1 * 4 =  4    2 * 4 =  8    3 * 4 = 12    4 * 4 = 16    
1 * 5 =  5    2 * 5 = 10    3 * 5 = 15    4 * 5 = 20    5 * 5 = 25    
1 * 6 =  6    2 * 6 = 12    3 * 6 = 18    4 * 6 = 24    5 * 6 = 30    6 * 6 = 36    
1 * 7 =  7    2 * 7 = 14    3 * 7 = 21    4 * 7 = 28    5 * 7 = 35    6 * 7 = 42    7 * 7 = 49    
1 * 8 =  8    2 * 8 = 16    3 * 8 = 24    4 * 8 = 32    5 * 8 = 40    6 * 8 = 48    7 * 8 = 56    8 * 8 = 64    
1 * 9 =  9    2 * 9 = 18    3 * 9 = 27    4 * 9 = 36    5 * 9 = 45    6 * 9 = 54    7 * 9 = 63    8 * 9 = 72    9 * 9 = 81    
还是竖打，但只需一次循环：
1 * 1 =  1    
1 * 2 =  2    2 * 2 =  4    
1 * 3 =  3    2 * 3 =  6    3 * 3 =  9    
1 * 4 =  4    2 * 4 =  8    3 * 4 = 12    4 * 4 = 16    
1 * 5 =  5    2 * 5 = 10    3 * 5 = 15    4 * 5 = 20    5 * 5 = 25    
1 * 6 =  6    2 * 6 = 12    3 * 6 = 18    4 * 6 = 24    5 * 6 = 30    6 * 6 = 36    
1 * 7 =  7    2 * 7 = 14    3 * 7 = 21    4 * 7 = 28    5 * 7 = 35    6 * 7 = 42    7 * 7 = 49    
1 * 8 =  8    2 * 8 = 16    3 * 8 = 24    4 * 8 = 32    5 * 8 = 40    6 * 8 = 48    7 * 8 = 56    8 * 8 = 64    
1 * 9 =  9    2 * 9 = 18    3 * 9 = 27    4 * 9 = 36    5 * 9 = 45    6 * 9 = 54    7 * 9 = 63    8 * 9 = 72    9 * 9 = 81