# | Submission time | Handle | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
522876 | 2022-02-06T08:36:43 Z | Cross_Ratio | Monochrome Points (JOI20_monochrome) | C++14 | 0 ms | 0 KB |
#include <bits/stdc++.h> #pragma GCC optimize("O3") #pragma GCC optimize("Ofast") #pragma GCC optimize("unroll-loops") #pragma GCC target ("avx2") using namespace std; struct SegTree { vector<int> seg; int MAX; void init(int N) { seg.resize(N+5); MAX = N+5; } void clear() { fill(seg.begin(),seg.end(),0); } int sum(int i) { int ans = 0; while(i>0) { //cout << i << ' ' << ans << '\n'; ans += seg[i]; i -= (i&-i); } return ans; } void Edit(int i, int a) { i++; while(i<MAX) { //cout << i << '\n'; seg[i] += a; i += (i & -i); } } int sum(int s, int e) { return sum(e)-sum(s); } }; SegTree tree; int used[200005] int simulate(vector<int> V) { //cout << "simul\n"; tree.clear(); fill(used,used+V.size()/2,-1); int ans = 0; int i; for(i=0;i<V.size();i++) { if(used[V[i]] != -1) { ans += tree.sum(used[V[i]]+1, i); tree.Edit(used[V[i]],-1); } else { tree.Edit(i, 1); used[V[i]] = i; } } return ans; } signed main() { cin.sync_with_stdio(false); cin.tie(0); cout.tie(0); int N; string s2; cin >> N >> s2; tree.init(2*N); int i, j, k; vector<int> A, B; for(i=0;i<2*N;i++) { if(s2[i]=='B') A.push_back(i); else B.push_back(i); } vector<int> V; V.resize(s2.length()); for(i=0;i<A.size();i++) V[A[i]] = i; int ans = -1; int s = 0, e = N - 1; while(e-s>=3) { int l = (2*s+e)/3; int r = (s+2*e)/3; for(int j = l; j < l + N; j++) { V[B[j%N]] = j-l; } int v1 = simulate(V); for(int j = r; j < r + N; j++) { V[B[j%N]] = j-r; } int v2 = simulate(V); if(v1<v2) s = l; else e = r; } for(i=s;i<=e;i++) { for(int j = i; j < i + N; j++) { V[B[j%N]] = j-i; } ans = max(ans, simulate(V)); } cout << ans; }