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package com.test;
/**
* 递归调用实例
* @author lanhongshi
* @createDate 2011-02-28
* @modifyDate
*/
public class Recursion {
/***
* x,x+n,x+2n ... y相乘 其中n为两个数之间的间隔 ,x为起始数 y为终点数
* @param start 起始数
* @param end 终点数
* @return 最终和
*/
public int total(int start,int step,int end){
int new_start=start+step;
if(new_start<=end){
return start*total(new_start,step,end);
}
return start;
}
private int[] createThree(int currentRow,int[] temps,int startRow,int lastRow ){
if(lastRow>=currentRow){
int[] temp={};
if(currentRow==1){
temp=temps;
}else{
int colum=currentRow+1;
temp=new int[colum];//新层构建
for(int i=1;i<colum-1;i++){
if(currentRow==2){
temp[i]=temps[i-1]*2;
}else{
temp[i]=temps[i-1]+temps[i];}
}
temp[0]=1;temp[colum-1]=1;
}
if(currentRow>=startRow&¤tRow<=lastRow){
for(int j=0;j<temp.length;j++){
System.out.print(temp[j]+" ");
}
System.out.println();
}
currentRow++;
return createThree(currentRow,temp,startRow,lastRow );
}else{
return new int[]{};
}
}
/**
* 杨辉三角
* @param start 起始行
* @param end 结束行
*/
public void createYHSJ(int start,int end){
createThree(1,new int[]{1},start,end);
}
}
public class YangHui2{
public static void main(String[] args){
java.util.Scanner sc=new java.util.Scanner(System.in);
System.out.println("请输入一个数:");
int num=sc.nextInt();
int[][] tr = new int[num][];
System.out.println("杨辉三角为:");
//算法部分
for(int i = 0; i < tr.length; i++){
tr[i] = new int[i + 1];
tr[i][0] = 1;
tr[i][i] = 1;
for(int j = 0; j < i; j++){
if(j >= 1 && i > 1){
tr[i][j] = tr[i - 1][j - 1] + tr[i - 1][j];
}
}
}
//输出部分
for(int i = 0; i < tr.length; i++){
for(int j = 0; j < tr.length - tr[i].length; j++){
System.out.print(" ");
}
for(int j = 0; j < tr[i].length; j++){
if(tr[i][j]>=10){
System.out.print(tr[i][j]);
System.out.print(" ");
}else{
System.out.print(tr[i][j]);
System.out.print(" ");
}
}
System.out.println();
}
}
}
public class Yanghui{
public static void main(String args[]){
final int ROW=9;//行数,为奇数
int i,j;
int a[][];
a=new int[ROW][ROW];
for(i=0;i<ROW;i++){
a[i][i]=1;
a[i][0]=1;
}
for(i=2;i<ROW;i++)
for(j=1;j<=ROW-1;j++)
a[i][j]=a[i-1][j-1]+a[i-1][j];
for(i=0;i<ROW;i++){
for(int m=1;m<33-2*i;m++)
System.out.print(" ");
for(j=0;j<=i;j++)
System.out.print(a[i][j]+" ");
System.out.println();
}
}
}
public class YangHui
{
public static void main(String args[])
{
final int ROW=13;
int a[][]=new int[ROW+1][];
for(int i=0;i<=ROW;i++)
{
a[i]=new int[i+1]; //指定每行的列数
}
yanghui(a,ROW);
}
static void yanghui(int a[][],int ROW)
{
for(int i=0;i<=ROW;i++)
for(int j=0;j<=a[i].length-1;j++)
{
if(i==0||j==0||j==a[i].length-1)
a[i][j]=1;
else a[i][j]=a[i-1][j-1]+a[i-1][j];
}
for(int i=0;i<=ROW;i++)
{
for(int j=0;j<=a[i].length-1;j++)
System.out.print(a[i][j]+"\t");
System.out.println();
}
}
}
public class Yanghui {
public static void main(String[] args) {
Yanghui yang = new Yanghui();
yang.printYanghuiTriangle(13);
}
/**
* 生成指定行数的杨辉三角形
*
* @param lines 杨辉三角形的行数
*/
public void printYanghuiTriangle(int lines) {
if(lines < 1) {
throw new IllegalArgumentException("lines must be great than 0.");
}
if(lines > 30) {
throw new IllegalArgumentException("lines is too big.");
}
int[] line = new int[lines];
int maxLen = getMaxLen(lines);
for(int i = 0; i < lines; i++) {
line[0] = line[i] = 1;
for(int j = 1, k = i / 2, pre = line[0]; j <= k; j++) {
int cur = line[j];
line[i - j] = line[j] += pre;
pre = cur;
}
printLine(line, i + 1, maxLen);
}
}
/**
* 根据指定行数的杨辉三角形,计算其中最大数字的长度
* @param lines 杨辉三角形的行数
* @return 最大数字的长度
*/
private int getMaxLen(int lines) {
int k = lines / 2;
long maxNum = factorial(k + 1, lines - 1) / factorial(1, lines - 1 - k);
return getLength(maxNum);
}
/**
* 阶乘计算
* @param start 阶乘计算的起始数字
* @param num 阶乘计算的终止数字
* @return 阶乘计算结果
*/
private long factorial(int start, int num) {
long result = start > 0 ? start : 1L;
while(num > start) {
result *= num--;
}
return result;
}
/**
* 根据指定数字计算数字的长度
* @param num 数字
* @return 数字的长度
*/
private int getLength(long num) {
int len = 0;
while(num > 0L) {
num /= 10L;
len++;
}
return len;
}
private void printLine(int[] yanghui, int line, int width) {
printSpaces((yanghui.length - line) * width);
for(int i = 0; i < line; i++) {
if(i > 0) {
printSpaces(width);
}
printSpaces(width - getLength(yanghui[i]));
System.out.print(yanghui[i]);
}
System.out.println();
if(width > 1) {
System.out.println();
}
}
private void printSpaces(int spaceCount) {
for(int i = 0; i < spaceCount; i++) {
System.out.print(" ");
}
}
}
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
1 8 28 56 70 56 28 8 1
1 9 36 84 126 126 84 36 9 1
1 10 45 120 210 252 210 120 45 10 1
1 11 55 165 330 462 462 330 165 55 11 1
1 12 66 220 495 792 924 792 495 220 66 12 1