汽水瓶 ----- 牛客

汽水瓶 ----- 牛客

遞歸
1 個空瓶 = 0 瓶汽水 + 0 個空瓶
2 個空瓶 = 1 瓶汽水 + 0 個空瓶
3 個空瓶 = 1 瓶汽水 + 1 個空瓶
f(1) = 0
f(2) = 0
f(3) = 1
f(4) = f(3 + 1)
= 1 瓶汽水 + 2 個空瓶
= 1 + f(2)
= 2 瓶汽水 + 0 個空瓶
f(5) = f(3 + 2)
= 1 瓶汽水 + 3 個空瓶
= 1 + f(3)
f(n) = 1 + f(n - 2)

import java.util.Scanner;
/**
 * Author: lisiyu
 * Created: 2020/3/3
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while (scanner.hasNext()) {
            n = scanner.nextInt();
            System.out.println(Drink(n));
        }
    }
    private static int Drink(int n) {
        if (n <= 0) {
            return 0;
        }
        if (n == 1) {
            return 0;
        }
        if (n == 2) {
            return 1;
        }
        return Drink(n - 2) + 1;
    }
}