数据结构与算法之母牛生牛

以你之姓@ 2021-12-15 00:05 197阅读 0赞

# 数据结构与算法之母牛生牛 #

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## 目录 ##

1.  字符凭拼接最低字典序
2.  二维数组最小路径和

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### 1. 字符凭拼接最低字典序 ###

1.  题目概述：母牛每年生一只小牛，新出生的母牛成长三年后也能每年生出一只母牛，假设不会死。求N年后，母牛的数量
2.  思路

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70]

1.  代码实现

public class Code_Cow {
        
    
    	public static int cowNumber1(int n) {
        
    		if (n < 1) {
        
    			return 0;
    		}
    		if (n == 1 || n == 2 || n == 3) {
        
    			return n;
    		}
    		return cowNumber1(n - 1) + cowNumber1(n - 3);
    	}
    
    	public static int cowNumber2(int n) {
        
    		if (n < 1) {
        
    			return 0;
    		}
    		if (n == 1 || n == 2 || n == 3) {
        
    			return n;
    		}
    		int res = 3;
    		int pre = 2;
    		int prepre = 1;
    		int tmp1 = 0;
    		int tmp2 = 0;
    		for (int i = 4; i <= n; i++) {
        
    			tmp1 = res;
    			tmp2 = pre;
    			res = res + prepre;
    			pre = tmp1;
    			prepre = tmp2;
    		}
    		return res;
    	}
    
    	public static void main(String[] args) {
        
    		int n = 20;
    		System.out.println(cowNumber1(n));
    		System.out.println(cowNumber2(n));
    	}
    
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MTkxMDY5NA_size_16_color_FFFFFF_t_70]: /images/20211214/f3bac31ce78446569f832bb0e8f213d9.png