> For the complete documentation index, see [llms.txt](https://anand-aryan.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://anand-aryan.gitbook.io/leetcode/91.-decode-ways.md).

# 91. Decode Ways

Decode Ways

A message containing letters from A-Z is being encoded to numbers using the following mapping:

'A' -> 1 'B' -> 2 ... 'Z' -> 26

Given an encoded message containing digits, determine the total number of ways to decode it.

For example, Given encoded message "12", it could be decoded as "AB" (1 2) or "L" (12).

The number of ways decoding "12" is 2.

## Solution <a href="#solution" id="solution"></a>

```java
public class Solution {
    public int numDecodings(String s) {
        int size = s.length();
        if (size == 0) return 0;
        int[] ways = new int[size + 1];
        ways[0] = 1;

        int temp = Integer.valueOf(s.substring(0,1));
        if (temp > 0 && temp <= 9) {
            ways[1] = 1;
        }

        for(int i = 2; i <= size; i ++) {
            int temp1 = Integer.valueOf(s.substring(i-1, i));
            if (temp1 > 0 && temp1 <= 9) {
                ways[i] += ways[i-1];
            }

            int temp2 = Integer.valueOf(s.substring(i-2, i));
            if (temp2>=10 && temp2 <=26) {
                ways[i] += ways[i-2];
            }

        }

        return ways[size];
    }
}
```