package LeetCode;/**

* @Classname DecodeWays

* @Description 本题和爬楼梯题目是相似的,应该考虑使用递归思想

* @Date 19-2-27 下午3:36

* @Created by mao<tianmao818@qq.com>

*/

public class DecodeWays {

public int numDecodings(String s) {

int result=0;

if(s.length()==0){

return 0;

}

if(s.length()==1){

return 1;

}

if(s.length()==2){

int a=s.charAt(0)-'0';

int b=s.charAt(1)-'0';

int num=a*10+b;

if(num>26){

return 1;

}else {

return 2;

}

}

if(s.length()>2){

for(int i=s.length()-1;i>=2;i--){

int a2=s.charAt(i)-'0';

int b2=s.charAt(i-1)-'0';

int num2=a2+b2*10;

if(num2<=26){

result=numDecodings(s.substring(0,i))+numDecodings(s.substring(0,i-1));

}else{

result=numDecodings(s.substring(0,i));

}

}

}

return result;

}

public static void main(String[] args){

DecodeWays decodeWays=new DecodeWays();

System.out.println(decodeWays.numDecodings("27"));

}

}