/**
* 刘云龙
*
* 2011-10-12
* 下午03:31:31
*/
package com.long3.util;
import java.util.Arrays;
/**
* @author 刘云龙 www.2cto.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);
}
return yanghui;
}
static int combin(int m, int n){
// System.out.println( p(n) * p(m-n) + "p(n) " + n + "p(m-n)" + (m-n));
// System.out.println( p(n) * p(m-n) + "p(n) " + p(n) + "p(m-n)" + p(m-n));
return p(m) / ( p(n) * p(m-n) );
}
static int p(int a){
if(a == 0){
return 1;
}
for(int i = a - 1; i >= 1; i--){
a *= i;
}
return a;
}
}
class timer{
static long beginTime ;
static long endTime;
static void begin(){
beginTime = System.currentTimeMillis();
}
static void end(){
endTime = System.currentTimeMillis();
}
static String getTime(){