[LeetCode] Decode ways (수정 예정)

class Solution {
public:
    int numDecodings(string s) {
        int p1=0,p2=1;
        for (int i=0,n; i<s.length(); i++) {
            n = 0;
            if (i==0) {
                if (s[i]=='0') return 0;
                n++;
            }
            else {
                int num = (int)(s[i-1]-'0') * 10 + (int)(s[i]-'0');     
                if (s[i]!='0') n += p2;
                if (s[i]=='0'&& (s[i-1]=='0' || num>26)) return 0; 
                else if (s[i-1]!='0' && num<=26) n += p1;
            }
            p1 = p2;
            p2 = n;
            cout << "p1 : " << p1 << " p2 : "<<p2 << endl;
        }
        return p2;
    }
};