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Purpose:
Use a two-dimensional array to print a 10-line Yang Hui triangle.
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Idea:
1. There is 1 element in the first row, and the nth row There are n elements;
2. The first element and the last element of each row are both 1;
3. Starting from the third row, for the non-first element and the last An element of an element. That is: yanghui[i][j] = yanghui[i-1][j-1] yanghui[i-1][j];
This is the array sum For the combination of nested loops, follow the prompts step by step, and the effect is as shown in the picture above.
Code implementation:
package com.atguigu.exer; import java.util.concurrent.ForkJoinPool; public class ArrayDemo { public static void main(String[] args) { //1.二维数组的动态初始化 int[][] yangHui = new int[10][]; //2.二维数组的外层元素的动态初始化 for(int i = 0;i < yangHui.length;i++){ yangHui[i] = new int[i + 1]; } //3. 给二维数组的内层元素赋值 for(int i = 0;i < yangHui.length;i++){ //3.1 每一行的首末元素赋值为1 yangHui[i][0] = yangHui[i][i] = 1; //3.2 每一行的非首末元素赋值。规律为:yanghui[i][j] = yanghui[i-1][j-1] + yanghui[i-1][j]; //if(i >= 2){ for(int j = 1;j < yangHui[i].length - 1;j++){ yangHui[i][j] = yangHui[i-1][j-1] + yangHui[i-1][j]; } //} } //4. 遍历二维数组 for (int i = 0; i < yangHui.length; i++) { for (int j = 0; j < yangHui[i].length; j++) { System.out.print(yangHui[i][j] + " "); } System.out.println(); } } }
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