类扩展欧几里得 zquoj 26659

 1 #include<bits/stdc++.h>
 2 #define pd putchar(‘ ‘)
 3 #define pn putchar(‘\n‘)
 4 #define pb push_back
 5 #define fi first
 6 #define se second
 7 #define f1(i,j,n) for(int i=j;i<n;i++)
 8 #define f2(i,j,n) for(int i=j;i<=n;i++)
 9 #define mem(i,j) memset(i,j,sizeof(i))
10 #define INF 0x3f3f3f3f
11 #define PI acos(-1.0)
12 #define ll long long
13 #define jiasu ios::sync_with_stdio(false)
14 #define P1 printf("YES\n")
15 #define P2 printf("NO\n")
16 const ll mod = 1e9 + 7 ;
17 const ll maxn = 1e5 + 10 ;
18 const double eps = 1e-8 ;
19 using namespace std;
20 ll solve(ll a,ll b,ll c,ll n){
21     
22     //a 公差 b 首项 c 除数 n 项数
23     if(n==1) return b/c;
24     if(n<=0) return 0;
25     ll ans=(a/c)*((n-1)*n/2);
26     ans+=(b/c)*n;
27     a%=c;b%=c;
28     if(a==0)return ans;
29     return ans+solve(c,(a*n+b)%c,a,(a*n+b)/c);
30 }
31 int main()
32 {
33     int t;
34     scanf("%d",&t);
35     while(t--){
36         ll p,q,n;
37         scanf("%lld%lld%lld",&p,&q,&n);
38         ll sum=p*n*(n+1)/2;
39         ll res=solve(p,p,q,n)*q;
40         printf("%lld\n",sum-res);
41     }
42     return 0;
43 }