黑马程序员：Java基础总结----多重For循环的解决数学问题

/*

九九乘法表
1*1=1
1*2=2 2*2=4
1*3=3 2*3=6 3*3=9

*/

for (int x=1; x<=9 ; x++)
{
for (int y=1; y<=x; y++)
{
System.out.print(y+"*"+x+"="+y*x+"\t");
}
System.out.println();
}

/*

----*
---* *
--* * *
-* * * *
* * * * *

* * * * *
-* * * *
--* * *
---* *
----*

*

for (int x=0; x<5 ;x++ )
{
for(int y=x+1; y<5 ; y++)
{
System.out.print(" ");
}
for(int z=0; z<=x ; z++)
{
System.out.print("* ");
}

System.out.println();
}

//百鸡百头问题

public static void main(String[] args) {
for (int ji = 0; ji <= 35; ji++) {
for (int tu = 0; tu <= 35; tu++) {
if (ji + tu == 35 && 2 * ji + 4 * tu == 94) {
System. out.println("鸡" + ji + "只\t" + "兔" + tu + "只" );
}
}
}

}

// 素数判断方法
boolean isSuShu(int num) {
for (int i = 2; i < num; i++) {
if (num % i == 0) {
return false ;
}
}
return true ;
}

//打印杨辉三角
void yagnhui() {
// 输入行数
// Scanner input = new Scanner(System.in);
System. out.println("请输入行数：" );
// int n = input.nextInt();
int n = 10;
int mat[][] = new int[n + 1][];
int i, j;
// 给二维赋值
for (i = 0; i < n + 1; i++) {
mat[i] = new int [i + 1];
mat[i][i] = 1;

for (j = 1; j < i; j++) {
mat[i][j] = mat[i - 1][j - 1] + mat[i - 1][j];
}
}
// 打印了
for (i = mat.length - 1; i >= 0; i--) {
for (int j2 = 0; j2 <mat.length-i; j2++) {
System. out.print(" " );
}
for (j = mat[i].length - 1; j > 0; j--)
System. out.print(" " + mat[i][j]);
System. out.println();
}
}