HDU4611+数学

 /*
 找规律
 题意：abs(i%A - i%B) 对i从0~N-1求和
 从0~N-1一个一个算必TLE，着A，B两者差相同的部分合并起来算
 */
 #include<stdio.h>
 #include<string.h>
 #include<stdlib.h>
 #include<algorithm>
 #include<iostream>
 #include<queue>
 #include<map>
 #include<math.h>
 using namespace std;
 typedef long long int64;
 //typedef __int64 int64;
 const int maxn = ;
 const int inf = 0x7fffffff;
 const double pi=acos(-1.0);
 const double eps = 1e-;

 int64 gcd( int64 a,int64 b ){
     int64 r;
     while( b ){
         r = a%b;
         a = b;
         b = r;
     }
     return a;
 }

 int64 lcm( int64 a,int64 b,int64 Gcd ){
     return a*b/Gcd;
 }

 int64 Abs( int64 a ){
     if( a< ) return -a;
     else return a;
 }

 int64 solve( int64 n,int64 a,int64 b ){
     int64 Index,tmpLen,res,Indexa,Indexb;
     res = Index = Indexa = Indexb = ;
     while( Index<n ){
         tmpLen = min( a-Indexa,b-Indexb );
         if( Index+tmpLen>n ) tmpLen = n-Index;//Index:表示新的开始分割的位置
         res += tmpLen*Abs( Indexa-Indexb );
         Indexa += tmpLen, Indexa %= a;
         Indexb += tmpLen, Indexb %= b;
         Index += tmpLen;
     }
     return res;
 }        

 int main(){
     int T;
     scanf("%d",&T);
     while( T-- ){
         int64 n,a,b;
         //scanf("%lld%lld%lld",&n,&a,&b);
         scanf("%I64d%I64d%I64d",&n,&a,&b);
         int64 LCM = lcm( a,b,gcd(a,b) );
         int64 ans = ;
         if( LCM>=n ) ans = solve( n,a,b );
         else ans = (n/LCM)*solve( LCM,a,b )+solve( n%LCM,a,b );
         //printf("%lld\n",ans);
         printf("%I64d\n",ans);
     }
     return ;
 }