bzoj4292 PA2015 Równanie 枚举

Posted 2020-10-21 Kaiser

貌似应该是找出n后，带回去看看是不是对的。

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #include<cmath>
 5 #include<iostream> 
 6 
 7 #define ll long long
 8 using namespace std;
 9 typedef long long LL;
10 const int MAXN=9*9*18;
11 ll k,a,b;
12 
13 ll solve(ll u)
14 {
15     ll n,sum,ret=0;
16     for(ll i=1;i<=MAXN;i++)
17     {
18         n=i*k;if(n>u) break;
19         sum=0;
20         while(n)
21         {
22             sum+=(n%10)*(n%10);
23             n/=10;
24         }
25         if(sum==i)ret++;
26     }
27     return ret;
28 }
29 int main()
30 {
31     scanf("%lld%lld%lld",&k,&a,&b);
32     printf("%lld\\n", solve(b)-solve(a-1));
33 }