Submission #979107

#TimeUsernameProblemLanguageResultExecution timeMemory
979107canadavid1Radio Towers (IOI22_towers)C++17
23 / 100
4059 ms4664 KiB
#include "towers.h" #include <vector> #include <numeric> #include <algorithm> #include <set> struct SegmentTree { private: std::vector<int> data; struct SegTreeReference { private: const int pos; SegmentTree& t; public: SegTreeReference(int pos,SegmentTree& t) : pos(pos), t(t) {} int operator=(int val) { t.assign(pos,val); return val; } operator int() const {return t.data[t.data.size()/2+pos];} }; public: SegmentTree() : data(0) {} SegmentTree(int num) : data(num*2,0) {} SegmentTree(const std::vector<int>& vec) : data(vec.size()*2) { for(int i = 0; i < vec.size(); i++) data[vec.size()+i] = vec[i]; for(int i = vec.size()-1; i > 0; i--) data[i] = std::max(data[2*i],data[2*i+1]); } void assign(int pos, int val) { data[pos] = val; pos >>= 1; for(;pos>0;pos>>=1) data[pos] = std::max(data[2*pos],data[2*pos+1]); } SegTreeReference operator[](int pos) { return SegTreeReference(pos,*this); } int query(int l, int r) { l += data.size()/2; r += data.size()/2; int o = -(1<<31); while(l < r) { if(l&1) o = std::max(o,data[l++]); if(r&1) o = std::max(o,data[--r]); l>>=1; r>>=1; } return o; } void push_back(int v) { int N = data.size()/2; data.push_back(data[N]); data.push_back(v); data[N] = std::max(data[2*N],data[2*N+1]); } }; std::vector<int> H; int m; void init(int N, std::vector<int> _H) { H = std::move(_H); } int max_towers(int L, int R, int D) { std::vector<int> idx_sorted(H.size()); SegmentTree st(H); std::iota(idx_sorted.begin(),idx_sorted.end(),0); std::sort(idx_sorted.begin(),idx_sorted.end(),[](auto a, auto b) {return H[a] < H[b];}); std::set<int> included; for(auto i : idx_sorted) { if(i < L || i > R) continue; auto p = included.lower_bound(i); if(p!=included.begin()) { auto l = *std::prev(p); l++; if(l==i) continue; if (st.query(l,i)-D < H[i]) continue; } if(p!=included.end()) { auto r = *p; if(r==i+1) continue; if(st.query(i+1,r)-D < H[i]) continue; } // bool inv = false; // for(auto j : included) // { // auto l = std::min(i,j); // l++; // auto r = std::max(i,j); // if(l==r) {inv = true;break;} // auto c = st.query(l,r); // if(H[i] > c-D || H[j] > c-D) {inv = true;break;} // } included.insert(i); } return included.size(); }

Compilation message (stderr)

towers.cpp: In constructor 'SegmentTree::SegmentTree(const std::vector<int>&)':
towers.cpp:31:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         for(int i = 0; i < vec.size(); i++) data[vec.size()+i] = vec[i];
      |                        ~~^~~~~~~~~~~~
towers.cpp: In member function 'int SegmentTree::query(int, int)':
towers.cpp:51:17: warning: integer overflow in expression of type 'int' results in '-2147483648' [-Woverflow]
   51 |         int o = -(1<<31);
      |                 ^~~~~~~~
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