3245. 找数

#include <bits/stdc++.h>
using namespace std;


void printAns(string& s){
    for (int i = s.length()-1; i >=0; i--) {
        if (s[i-1]>s[i]){
            s[i-1]=s[i-1]-1;
            for (int j = i; j < s.length(); ++j) {
                s[j]='9';
            }
        }
    }
    cout<<s.substr(s.find('0')+1)<<endl;
}

int main() {
    int t;
    string s;
    cin>>t;
    for (int p = 0; p < t; ++p) {
        cin>>s;
        cout<<"case #"<<p<<":"<<endl;
        if (s.length() == 1) cout<<s<<endl;
        else printAns(s);
    }

    return 0;
}

#include <bits/stdc++.h>

using namespace std;

void print_int(string n) {
    auto it = n.begin();
    for (; *it == '0' && it <= n.end(); it++);
    string tmp(it, n.end());
    cout << tmp << endl;
}

int main() {
    int T;
    string n;
    cin >> T;
    for (int i = 0; i < T; ++i) {
        cin >> n;
        if (n.length() == 1) {
            cout << "case #" << i << ":" << endl;
            cout << n << endl;
            continue;
        }
        for (auto it = n.begin() + 1; it < n.end(); it++) {
            if (*it < *(it - 1)) {
                // 逆向查找
                auto it_r = it - 1;
                while (it_r != n.begin() && *(it_r - 1) == *it_r) {
                    it_r--;
                }
                *it_r = *it_r - 1;
                it_r++;
                while (it_r != n.end()) {
                    *it_r = '9';
                    it_r++;
                }
                break;
            }
        }
        cout << "case #" << i << ":" << endl;
        print_int(n);
    }

    return 0;
}

#include <bits/stdc++.h>
using namespace std;
void solve(string &s)
{
    for(int i=s.size()-2;i>=0;i--)
    {
        if(s[i]>s[i+1])
        {
            for(int j=i+1;j<s.size();j++)
                s[j]='0';
            for(int j=i;j<s.size();j++)
            {
                if(j==i)
                    s[j]=s[j]-1;
                else
                    s[j]='9';
            }
        }
    }
}
int main()
{
    int cas;
    cin>>cas;
    for(int i=0;i<cas;i++)
    {
        string s;
        cin>>s;
        printf("case #%d:\n",i);
        solve(s);
        bool ok=0;
        for(int i=0;i<s.size();i++)
        {
            if(s[i]!='0')
                ok=1;
            if(ok==1)
                cout<<s[i];
        }
        cout<<endl;
    }
    return 0;
}

#include <iostream>
#include <string>
using namespace std;

void solve() {
    string str;
    cin >> str;
    for (int i = 1; i < str.size(); ++i) {
        while (str[i] < str[i - 1]) {
            for (int j = i; j < str.size(); ++j)
                str[j] = '9'; // 后面的置9。
            while (--str[--i] < '0')
                str[i] = '9'; // 退位。
        }
    }
    printf("%s\n", str.substr(str.find_first_not_of('0')).data());
}

int main() {
    int t;
    cin >> t;
    for (int i = 0; i < t; ++i) {
        printf("case #%d:\n", i);
        solve();
    }
}