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| Time Limit: 1000MS | Memory Limit: 30000K | |
| Total Submissions: 13378 | Accepted: 4026 |
Description
Alice: "Let‘s just use a very simple code: We‘ll assign ‘A‘ the code word 1, ‘B‘ will be 2, and so on down to ‘Z‘ being assigned 26."
Bob: "That‘s a stupid code, Alice. Suppose I send you the word ‘BEAN‘ encoded as 25114. You could decode that in many different ways!”
Alice: "Sure you could, but what words would you get? Other than ‘BEAN‘, you‘d get ‘BEAAD‘, ‘YAAD‘, ‘YAN‘, ‘YKD‘ and ‘BEKD‘. I think you would be able to figure out the correct decoding. And why would you send me the word ‘BEAN’ anyway?”
Bob: "OK, maybe that‘s a bad example, but I bet you that if you got a string of length 500 there would be tons of different decodings and with that many you would find at least two different ones that would make sense."
Alice: "How many different decodings?"
Bob: "Jillions!"
Input
Output
Sample Input
25114 1111111111 3333333333 0
Sample Output
6 89 1
分析：因为题目给的都是正常数据，所以不会出现两个0连在一起的情况。这道题要十分注意有0出现的情况（因为0 WA了好几次。。，我本来以为题目中会有非合法的情况出现的，比如1002，WA之后还把02当做一个数也试了试，依旧WA。。看了discuss的测试数据才知道这么想是错的），当有0出现时，说明前面的那个数肯定是1或2，可以和这个0配对，所以result[i] = result[i - 2]。对于非0 的情况，如果前面的数是1，则当前的数可以单独作为一个数存在(result[i - 1]种情况)，也可以和前面的1配对存在(result[i - 2]种情况)，当前面的数是2，当前的数大于0小于7时也是这种情况。否则的话就是只能当前的数作为单独的一个数存在了，有result[i - 1]种情况。
Java AC 代码
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String str = ""; char[] input; long[] result; while(!(str = sc.next()).equals("0")) { input = str.toCharArray(); int len = input.length; result = new long[len]; result[0] = 1; if(len == 1) { System.out.println(1); continue; } if(input[1] == ‘0‘) result[1] = 1; else if(input[0] == ‘1‘ || input[0] == ‘2‘ && input[1] < ‘7‘) result[1] = 2; else result[1] = 1; for(int i = 2; i < len; i++) { if(input[i] == ‘0‘) result[i] = result[i - 2]; else if(input[i - 1] == ‘1‘ || input[i - 1] == ‘2‘ && input[i] < ‘7‘) result[i] = result[i - 2] + result[i - 1]; else result[i] = result[i - 1]; } System.out.println(result[len - 1]); } } }
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原文地址：http://www.cnblogs.com/kkkkkk/p/5546707.html
