java 实现打印杨辉三角

package com.shan;

import java.util.Scanner;

public class YFTriangle {

public sta
ac15
tic void main(String[] args) {
printYFTriangle();
}

/**
* 1 要理解下面的实现，首先要明白int数组中元素默认值为 0
* 2 然后每一次迭代打印新的一行的元素的时候：
* 新的特定位置的元素 = 该位置原来的元素 + 该位置的前一个位置的值
*/
public static void printYFTriangle(){
System.out.println("how many lines you want:");
Scanner in = new Scanner(System.in);
int lines = in.nextInt();
int[] a = new int[lines + 1];
int previous = 1;
for (int i = 1; i <= lines; i ++){
for (int j = 1; j <= i; j++){
int current = a[j];
a[j] = previous + current;
previous = current;
System.out.print(a[j] + " ");
}
System.out.println();
}
}

}