#include "leetcode.h"

class Solution {
public:
  int numDecodings(string s) {
    int n = s.size();
    vector<int> dp(n + 1, 0);
    dp[0] = 1;
    for (int i = 0; i < n; ++i) {
      if (s[i] != '0')
        dp[i + 1] += dp[i];
      if (i >= 1 &&
          (s[i - 1] == '1' || (s[i - 1] == '2' && s[i] >= '0' && s[i] <= '6')))
        dp[i + 1] += dp[i - 1];
    }
    return dp[n];
  }
};

int main() {
  Solution obj;
  cout << obj.numDecodings("226");
}