思路

要从2开始，前两个状态要有初始值

class Solution {
public:
    int getTranslationCount(string s) {
        int n =s.size();
        vector<int> dp(n + 1);
        dp[0] = 1;
        dp[1] = 1;

        for (size_t i = 2; i <=n; ++i) {
            dp[i] = dp[i - 1];
            auto num = (s[i-2]-'0')*10 + s[i-1]-'0';
            if (num >= 10 && num <= 25)
                dp[i] += dp[i - 2];
        }
        return dp[n];
    }
};