约瑟夫斯 俄国农夫

package com.zhp.减常因子;

public class Josephus {

	public static void main(String[] args) {
		int total = 41;
		int answer = getResult(total);
		System.out.println("存活的人是：" +answer);
	}

	/**
	 * @param total
	 *            总人数
	 */
	public static int getResult(int total) {
		int answer = 0;
		if (total == 1) {
			// 总数只有一个时，存活的是第一个人
			return 1;
		}

		if (total % 2 == 0) {
			// 偶数
			answer = 2 * getResult(total / 2) - 1;
		} else {
			// 奇数
			answer = 2 * getResult((total - 1) / 2) + 1;
		}

		return answer;
	}
}

package com.zhp.减常因子;

public class RusMul {

	public static void main(String[] args) {
		int n = 50, m = 65;
		int answer = getResult(n, m);
		System.out.println(answer);
	}
	
	public static int getResult(int n, int m){
		int answer = 0;
		if(n == 1){
			return m;
		}
		if( n%2 == 0){
			//n 是偶数
			n = n/2;
			m = 2*m;
			answer = getResult(n, m);
		}else{
			//n 是奇数
			n = (n - 1)/2;
			m = 2*m;
			answer = getResult(n, m) + m/2;
		}
		return answer;
	}

}