Question

java 用嵌套循环编数字金字塔

金字塔形式如下：
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
如果再倒过来呢？

Answer 1

public class A {

public static void main(String[] args) {

int num = 6;
for (int i = 1; i <= num; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(j+" ");
}
System.out.println();
}
}
}
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6

把for (int j = 1; j <= i; j++) { 变成for (int j = 1; j <= num-i; j++) {
1 2 3 4 5
1 2 3 4
1 2 3
1 2
1

Answer 2

两个for循环即可

Answer 3

public class DemoTest {

/**
* @param args
*/
public static void main(String[] args) {
printNum(5);
printNumOrder(5);
}

private static void printNum(int num){
for (int i = 1; i <= num; i++) {
for (int j = 0; j < i; j++) {
System.out.print(j+1);
}
System.out.println();
}
}

private static void printNumOrder(int num){
for (int i = num; i >= 1; i--) {
for (int j = i; j >= 1; j--) {
System.out.print(j);
}
System.out.println();
}
}
}