java 二项式

/**
* 刘云龙
*
* 2011-10-12
* 下午03:31:31
*/
package com.long3.util;

import java.util.Arrays;

/**
* @author 刘云龙 www.zzzyk.com
*
*/
public class LeftMove {
    public static void main(String args[]) {
        try {
            timer.begin();
            for(int i = 0; i < 100; i++)
            Arrays.toString(yanghui3(20));
            timer.end();
            System.out.println(timer.getTime());


            timer.begin();for(int i = 0; i < 100; i++)
            Arrays.toString(yanghui2(20));
            timer.end();
            System.out.println(timer.getTime());


            timer.begin();for(int i = 0; i < 100; i++)
            Arrays.toString(yanghui(20));
            timer.end();
            System.out.println(timer.getTime());


        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    int[] createArray(int size) {
        return new int[size];
    }

    static int[][] yanghui(int level) throws IllegalAccessException {
        if (level <= 0) {
            throw new IllegalAccessException("参数不能为负值或为0 ：现在的 level = "
                    + level);
        }
        int[][] yanghui = new int[level][level];

        if (level >= 1) {
            yanghui[0][0] = 1;
        }
        if (level >= 2) {
            yanghui[1][0] = 1;
            yanghui[1][1] = 1;
        }

        for (int row = 2; row < level; row++) {
            yanghui[row][0] = 1;
            for (int col = 1; col < level - 1; col++) {
                yanghui[row][col] = yanghui[row - 1][col - 1]
                        + yanghui[row - 1][col];
            }
            yanghui[row][row] = 1;
        }

        return yanghui;
    }

    static int[] yanghui2(int level) throws IllegalAccessException {
        if (level <= 0) {
            throw new IllegalAccessException("参数不能为负值或为0 ：现在的 level = "
                    + level);
        }
        int[] yanghui = new int[level];

        if (level >= 1) {
            yanghui[0] = 1;
        }
        if (level >= 2) {
            yanghui[1] = 1;
        }

        for (int i = 2; i < level; i++) {
            yanghui[i] = 1;
            for (int j = i - 1; j >= 1; j--){ // 从左向右加，去掉 i 和 0 位置不参加计算
                yanghui[j] = yanghui[j] + yanghui[j - 1];
            }
        }

        return yanghui;
    }


    static int[] yanghui3(int level) throws IllegalAccessException{
        if (level <= 0) {
            throw new IllegalAccessException("参数不能为负值或为0 ：现在的 level = "
                    + level);
        }
        int[] yanghui = new int[level + 1];

        for(int i=0; i < level + 1; i++){
            yanghui[i] = combin(level, level-i);
        }

补充：软件开发 , Java ,