JAVA三道编程题

package java_chapt1;

import java.math.BigDecimal;

public class PowTest {
	public static void main(String[] args) {
		double num1 = 0.2;int num2 = 5;
		System.out.println(pow(num1,num2));
	}
	public static String pow(double num1,int num2) {
		BigDecimal num = new BigDecimal("1");
		BigDecimal num3 = new BigDecimal(String.valueOf(num1));
		for(int i=1;i<=num2;i++) {
			num = num.multiply(num3);
		}
		return num.toPlainString();
	}
}

package java_chapt1;

public class HametonTest {

	public static void main(String[] args) {
		int num1 = 1,num2 = 2;
		System.out.println(compare(getBinary(num1),getBinary(num2)));
	}
	
	public static int getBinary(int num) {
		String num1 = "";
		while(num>0) {
			num1 = num%2 + num1;
			num /= 2;
		}
		return Integer.parseInt(num1);
	}

	public static int compare(int num1,int num2) {
		int cnt = 0;
		while(num1>0||num2>0) {
			if((num1%10)!=(num2%10)) ++cnt;
			num1 /= 10;
			num2 /= 10;
		}
		return cnt;
	}
}

package java_chapt1;

import java.util.Arrays;

public class TriangleTest {

	public static void main(String[] args) {
		int num = 4;
		int num1 = 3;
		int arr[] = {2,2,3,4};
		int count = getCount(num,num1);
		int arr1[][] = getAll(num,count,num1,arr);
		System.out.println(Arrays.deepToString(arr1));
		System.out.println(getTriangleCount(arr1));
	}
	
	public static int getFactorial(int num,int num1) {
		if(num1==1) return num;
		return num*getFactorial(num-1,--num1);
	}
	
	public static int getCount(int num,int num1) {
		return getFactorial(num,num1)/getFactorial(num1,num1);
	}
	
	public static int[][] getAll(int num,int rowcount,int colcount,int arr[]){
		int rowidx = 0;
		int colidx = 0;
		int arr1[][] = new int[rowcount][colcount];
		for(int i=0;inum3&&(num1+num3)>num2&&(num2+num3)>num1) ++count;
		}
		return count;
	}
}