ADDED   SRM/528/2C.cpp
Index: SRM/528/2C.cpp
==================================================================
--- SRM/528/2C.cpp
+++ SRM/528/2C.cpp
@@ -0,0 +1,154 @@
+#include <iostream>
+#include <sstream>
+#include <iomanip>
+#include <vector>
+#include <string>
+#include <map>
+#include <set>
+#include <algorithm>
+#include <numeric>
+#include <iterator>
+#include <functional>
+#include <complex>
+#include <queue>
+#include <stack>
+#include <cmath>
+#include <cassert>
+#include <cstring>
+#ifdef __GNUC__
+#include <ext/hash_map>
+#define unordered_map __gnu_cxx::hash_map
+#else
+#include <unordered_map>
+#endif
+using namespace std;
+typedef long long LL;
+typedef complex<double> CMP;
+
+class Mosquitoes { public:
+	int getMaximum(vector <int> xInit, vector <int> v, int R)
+	{
+		vector< pair<double,double> > tx;
+		for (int i = 0; i < xInit.size(); i++)
+			for (int j = i+1; j < xInit.size(); j++)
+				critical_points(xInit[i], v[i], xInit[j], v[j], R, &tx);
+
+		int best = 1;
+		for(int i=0; i<tx.size(); ++i) {
+			double t = tx[i].first;
+			double x = tx[i].second;
+			if( t >= 0 ) {
+				int cnt = 0;
+				for (int k = 0; k < xInit.size(); k++)
+					if( is_in(xInit[k], v[k], t, x, R) )
+						++cnt;
+				best = max(best, cnt);
+			}
+		}
+		return best;
+	}
+
+	void critical_points(double x1, double v1, double x2, double v2, double R,
+		vector< pair<double,double> >* tx)
+	{
+		// Compute t such that | (x1 + t v1) - (x2 - t v2) | = 2R
+		double x = x1 - x2;
+		double v = v1 - v2;
+		if( v == 0 ) {
+			if( abs(x) <= 2*R )
+				tx->push_back( make_pair(0, (x1+x2)/2) );
+		} else {
+			double t1 = (2*R - x) / v;
+			double t2 = (2*R + x) / (-v);
+			tx->push_back( make_pair(t1, (func(x1,v1,t1)+func(x2,v2,t1))/2) );
+			tx->push_back( make_pair(t2, (func(x1,v1,t2)+func(x2,v2,t2))/2) );
+		}
+	}
+
+	double func(double x, double v, double t)
+	{
+		return x + v*t;
+	}
+
+	bool is_in(double x, double v, double t, double c, double R)
+	{
+		return abs(func(x,v,t) - c) <= R + 1e-8;
+	}
+};
+
+// BEGIN CUT HERE
+#include <ctime>
+double start_time; string timer()
+ { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
+template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
+ { os << "{ ";
+   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
+   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
+void verify_case(const int& Expected, const int& Received) {
+ bool ok = (Expected == Received);
+ if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
+ cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
+#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
+#define END	 verify_case(_, Mosquitoes().getMaximum(xInit, v, R));}
+int main(){
+
+CASE(0)
+	int xInit_[] = {1, -1};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {1, -1};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 10; 
+	int _ = 2; 
+END
+CASE(1)
+	int xInit_[] = {100, -100};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {1, -1};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 10; 
+	int _ = 1; 
+END
+CASE(2)
+	int xInit_[] = {0, -1, 10, -11, 99, -99};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {1, -1, -3, 3, 47, -47};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 3; 
+	int _ = 4; 
+END
+CASE(3)
+	int xInit_[] = {5};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {2};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 8; 
+	int _ = 1; 
+END
+CASE(4)
+	int xInit_[] = {12,34,56,78,90};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {-1,2,-3,4,-5};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 6; 
+	int _ = 3; 
+END
+CASE(5)
+	int xInit_[] = {-29, -27};
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = {25, 61};
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = 7; 
+	int _ = 2; 
+END
+/*
+CASE(6)
+	int xInit_[] = ;
+	  vector <int> xInit(xInit_, xInit_+sizeof(xInit_)/sizeof(*xInit_)); 
+	int v_[] = ;
+	  vector <int> v(v_, v_+sizeof(v_)/sizeof(*v_)); 
+	int R = ; 
+	int _ = ; 
+END
+*/
+}
+// END CUT HERE