ADDED   SRM/682-U/1A.cpp
Index: SRM/682-U/1A.cpp
==================================================================
--- SRM/682-U/1A.cpp
+++ SRM/682-U/1A.cpp
@@ -0,0 +1,144 @@
+#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 <tuple>
+#include <cstring>
+using namespace std;
+typedef long long LL;
+typedef complex<double> CMP;
+
+LL nei[2000][32];
+
+class SmilesTheFriendshipUnicorn { public:
+	string hasFriendshipChain(int N, vector <int> A, vector <int> B)
+	{
+		return solve(N, A, B) ? "Yay!" : ":(";
+	}
+
+	bool solve(int N, const vector<int>& A, const vector<int>& B)
+	{
+		vector<vector<int>> G(N);
+		for(int i=0; i<A.size(); ++i) {
+			G[A[i]].push_back(B[i]);
+			G[B[i]].push_back(A[i]);
+		}
+
+		memset(&nei, 0, sizeof(nei));
+
+		for(int i=0; i<A.size(); ++i) {
+			for(int u: G[A[i]])
+				nei[i][u>>6] |= 1LL<<(u&0x3f);
+			for(int u: G[B[i]])
+				nei[i][u>>6] |= 1LL<<(u&0x3f);
+			nei[i][A[i]>>6] &= ~(1LL<<(A[i]&0x3f));
+			nei[i][B[i]>>6] &= ~(1LL<<(B[i]&0x3f));
+		}
+
+		for(int i=0; i<A.size(); ++i)
+		for(int k=i+1; k<A.size(); ++k)
+		if(A[i]!=A[k] && A[i]!=B[k] && B[i]!=A[k] && B[i]!=B[k])
+			for(int v=0; v<32; ++v)
+				if(nei[i][v] & nei[k][v])
+					return true;
+		return false;
+	}
+};
+
+// 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 string& Expected, const string& 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(_, SmilesTheFriendshipUnicorn().hasFriendshipChain(N, A, B));}
+int main(){
+
+CASE(0)
+	int N = 5; 
+	int A_[] = {0, 1, 2, 3};
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {1, 2, 3, 4};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = "Yay!"; 
+END
+CASE(1)
+	int N = 5; 
+	int A_[] = {0, 1, 2, 3, 1};
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {1, 2, 3, 0, 4};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = "Yay!"; 
+END
+CASE(2)
+	int N = 6; 
+	int A_[] = {0, 0, 0, 0, 0};
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {1, 2, 3, 4, 5};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = ":("; 
+END
+CASE(3)
+	int N = 8; 
+	int A_[] = {1, 3, 4, 3, 4, 3, 0, 2};
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {7, 7, 7, 4, 6, 5, 4, 7};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = "Yay!"; 
+END
+CASE(4)
+	int N = 7; 
+	int A_[] = {0, 1, 1, 5, 4, 5};
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {5, 2, 3, 6, 1, 1};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = ":("; 
+END
+CASE(5)
+	int N = 42; 
+	int A_[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41}
+;
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 0};
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = "Yay!"; 
+END
+/*
+CASE(6)
+	int N = ; 
+	int A_[] = ;
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = ;
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = ; 
+END
+CASE(7)
+	int N = ; 
+	int A_[] = ;
+	  vector <int> A(A_, A_+sizeof(A_)/sizeof(*A_)); 
+	int B_[] = ;
+	  vector <int> B(B_, B_+sizeof(B_)/sizeof(*B_)); 
+	string _ = ; 
+END
+*/
+}
+// END CUT HERE

ADDED   SRM/682-U/1B.cpp
Index: SRM/682-U/1B.cpp
==================================================================
--- SRM/682-U/1B.cpp
+++ SRM/682-U/1B.cpp
@@ -0,0 +1,187 @@
+#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 <tuple>
+using namespace std;
+typedef long long LL;
+typedef complex<double> CMP;
+
+set<int> detect_cycle(int N, const vector<vector<int>>& G)
+{
+	vector<int> stk;
+	set<int> cycle;
+	function<void(int,int)> rec = [&](int pre, int v) {
+		stk.push_back(v);
+		for(int u: G[v]) if(u != pre) {
+			auto it = find(stk.begin(), stk.end(), u);
+			if(it == stk.end()) {
+				rec(v, u);
+			} else {
+				cycle = set<int>(it, stk.end());
+			}
+		}
+		stk.pop_back();
+	};
+	rec(-1, 0);
+	return cycle;
+}
+
+vector<vector<int>> flatten(const vector<set<int>>& GS)
+{
+	vector<vector<int>> G;
+	for(const auto& s: GS)
+		G.emplace_back(s.begin(), s.end());
+	return G;
+}
+
+class SuccessfulMerger { public:
+	int minimumMergers(vector <int> road)
+	{
+		const int N = road.size();
+		vector<set<int>> Gs(N);
+		for(int i=0; i<N; ++i) {
+			Gs[i].insert(road[i]);
+			Gs[road[i]].insert(i);
+		}
+		vector<vector<int>> G = flatten(Gs);
+
+		set<int> cy = detect_cycle(N, G);
+		if(cy.empty())
+			return solve(N, G);
+
+		int best = N-1;
+		set<int> cyl = cy;
+		for(int survive: cyl) {
+			cy.erase(survive);
+
+			map<int,int> remap;
+			int XN = N - cy.size() + 1;
+			for(int v=0; v<N; ++v) {
+				if(cy.count(v)) {
+					remap[v] = XN - 1;
+				} else {
+					int idx = 0;
+					for(int u=0; u<v; ++u)
+						if(!cy.count(u))
+							++idx;
+					remap[v] = idx;
+				}
+			}
+			vector<set<int>> XGs(XN);
+			for(int i=0; i<N; ++i) {
+				int a = remap[i];
+				int b = remap[road[i]];
+				if(a != b) {
+					XGs[a].insert(b);
+					XGs[b].insert(a);
+				}
+			}
+			vector<vector<int>> XG = flatten(XGs);
+			best = min<int>(best, solve(XN, XG) + cy.size() - 1);
+
+			cy.insert(survive);
+		}
+		return best;
+	}
+
+	int solve(int N, const vector<vector<int>>& G) {
+		if(N <= 2)
+			return 0;
+
+		int best = N-1;
+		for(int root=0; root<N; ++root)
+			best = min(best, solve(N, root, G));
+		return best;
+	}
+
+	int solve(int N, int root, const vector<vector<int>>& G)
+	{
+		function<int(int,int)> non_leaf_cnt = [&](int pre, int v) {
+			if(G[v].size() == 1)
+				return 0;
+			int sum = 1;
+			for(int u: G[v]) if(u != pre)
+				sum += non_leaf_cnt(v, u);
+			return sum;
+		};
+
+		int total = 0;
+		for(int ch: G[root])
+			total += non_leaf_cnt(root, ch);
+		return total;
+	}
+};
+
+// 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(_, SuccessfulMerger().minimumMergers(road));}
+int main(){
+
+CASE(0)
+	int road_[] = {2, 2, 1, 1, 1};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 1; 
+END
+CASE(1)
+	int road_[] = {3, 4, 5, 4, 5, 3};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 2; 
+END
+CASE(2)
+	int road_[] = {1, 0, 1, 0, 0, 0, 1, 0, 1, 1};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 1; 
+END
+CASE(3)
+	int road_[] = {1, 2, 3, 0};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 2; 
+END
+CASE(4)
+	int road_[] = {31, 19, 0, 15, 30, 32, 15, 24, 0, 20, 40, 1, 22, 21, 39, 28, 0, 23, 15, 5, 19, 22, 6, 32, 8, 38, 35, 30, 4, 28, 32, 18, 18, 9, 22, 41, 20, 18, 6, 25, 41, 34, 4};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 25; 
+END
+CASE(5)
+	int road_[] = {1, 0};
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = 0; 
+END
+/*
+CASE(6)
+	int road_[] = ;
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = ; 
+END
+CASE(7)
+	int road_[] = ;
+	  vector <int> road(road_, road_+sizeof(road_)/sizeof(*road_)); 
+	int _ = ; 
+END
+*/
+}
+// END CUT HERE