看了看题解， 有人说本质是 F(x)=x去掉最高位+x去掉最低位，我举双手赞成

但是假设答案为ABC (C位数最低) ，F(x)=AB+BC=y

为什么推导公式是11 * B == y - C - A * pow（10，len）啊

不应该是11 * B == y - C - A * pow（10，len（B））吗？B对A应该有约束吧，百思不得其解

偷偷拿一份别人ac的代码看看是怎么个事

#include <bits/stdc++.h>

using namespace std;

typedef long long LL;
const int N = 20;

int ans, T;
string s;

int main()
{
    cin >> T;
    while(T --)
    {
       ans = 0;
        LL a;
	   cin >> a;
	   for(int i = 1; i <= 9; ++ i)
		  for(int j = 0; j <= 9; ++ j)
		  {
			 for(LL k = 1; k <= 1e17; k *= 10)
			 {
				LL b = a - i * k - j;
				if(b % 11 == 0 && b >= 0 && k > b / 11) {
                    cout<<i<<b/11<<j<<' ';cout<<i*k+j+b<<'\n';
                    ans ++;
                }
			 }
		}
	   cout << ans << endl;
    }
	return 0;
}
/*
5
123456789
987654321
555555555
100000000000000000
99999999999999999
*/
 

跑的结果为

121324354 123456789
294051627 123456789
384960718 123456789
475869809 123456789
657687990 123456789
748597081 123456789
839506172 123456789
930415263 123456789
8
1806958474 987654321
2716049383 987654321
3625140292 987654321
4534231201 987654321
5443322110 987654321
7261503929 987654321
8170594838 987654321
979685747 987654321
8
1414141414 555555555
2323232323 555555555
3232323232 555555555
4141414141 555555555
550505050 555555555
5
100 100000000000000000
181818181818181819 100000000000000000
272727272727272728 100000000000000000
363636363636363637 100000000000000000
454545454545454546 100000000000000000
545454545454545455 100000000000000000
636363636363636364 100000000000000000
727272727272727273 100000000000000000
818181818181818182 100000000000000000
99090909090909091 100000000000000000
10
181818181818181818 99999999999999999
272727272727272727 99999999999999999
363636363636363636 99999999999999999
454545454545454545 99999999999999999
545454545454545454 99999999999999999
636363636363636363 99999999999999999
727272727272727272 99999999999999999
818181818181818181 99999999999999999
99090909090909090 99999999999999999
9

我承认i*k+j+b==y

但是F(121324354)=12132435+21324354=33456789肯定不等于123456789

还有10e17那个样例，明显的b是多个0组成，明显不应该啊

下面是我wawawa的代码

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mod 100000000
#define PII pair<int, int>
#define N 200005
ll n, m,ns,mp[10][20];
void solve()
{
    cin>>n;ns=0;
    ll ans=0;
    ll nn=n;while(nn)ns++,nn=nn/10;
    for(ll a=1;a<=9;a++){
        for(ll c=0;c<=9;c++){
            for(ll bns=0;bns<=16;bns++){
                if((n-mp[a][bns]-c)<0||(n-mp[a][bns]-c)%11!=0)continue;
                if(bns==0){
                    if(a+c==n){
                        cout<<a<<c<<'\n';//cout<<a+c<<'\n';
                        ans++;
                    }
                }else{
                    ll b=(n-mp[a][bns]-c)/11,mi=(bns==1?0:mp[1][bns-1]),mx=mp[1][bns];
                    if(b>=mi&&b<mx){
                        cout<<a<<b<<c<<'\n';//cout<<mp[a][bns]+b*11+c<<'\n';
                        ans++;
                    }
                }
            }
        }
    }
    cout<<ans<<'\n';
}
int main()
{
//	ios::sync_with_stdio(false);
//	cin.tie(0);
//	cout.tie(0);
	int _ = 1;
    for(int i=1;i<=9;i++){
        mp[i][0]=i;
        for(int k=1;k<=16;k++)mp[i][k]=mp[i][k-1]*10;
    }
	cin >> _;
	while (_--){
        solve();
	}
	return 0;
}

294051627
384960718
475869809
657687990
748597081
839506172
930415263
7
1806958474
2716049383
3625140292
4534231201
5443322110
7261503929
8170594838
7
1414141414
2323232323
3232323232
4141414141
4
181818181818181819
272727272727272728
363636363636363637
454545454545454546
545454545454545455
636363636363636364
727272727272727273
818181818181818182
8
181818181818181818
272727272727272727
363636363636363636
454545454545454545
545454545454545454
636363636363636363
727272727272727272
818181818181818181
8

也有可能是我题意还是没搞懂？有无神牛帮我解解惑，，，