Codeforces Round #555 (Div. 3) A - Reachable Numbers

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/xiang_6/article/details/89738821

直接模拟这个过程，次数不会超过 数的位数*10

#include <bits/stdc++.h>
#include <iostream>
using namespace std;
typedef long long ll;

const int maxn = 3e5 + 7;

int n;
set<int> st;

void solve(int n) {
    int t = n+1;
    while(t%10 == 0) t /= 10;
    if(st.count(t)) return;
    st.insert(t);
    solve(t);
}

int main() {
    cin >> n;
    st.insert(n);
    solve(n);
    cout << st.size() << endl;
    return 0;
}