Submission #1079674

#TimeUsernameProblemLanguageResultExecution timeMemory
1079674allin27xRadio Towers (IOI22_towers)C++17
14 / 100
883 ms22720 KiB
#include <bits/stdc++.h> using namespace std; #define int long long const int MAXN = 1e5+4; vector<int> h; vector<int> lc,rc,a; int pr[MAXN]; int inited = 0; vector<int> usef; map<int,int> nxt; map<int,int> prv; int sum (int l, int r) { if (l > r) return 0; if (r==0) return pr[r]; return pr[r] - pr[l-1]; } int dfs(int i, int d){ if (i==-1) return 0; if (lc[i]==-1 && rc[i]==-1) return -a[i]; int lans = dfs(lc[i],d); int rans = dfs(rc[i],d); if (lans < 0 && a[i] - d >= -lans) lans = 1; if (rans < 0 && a[i] - d >= -rans) rans = 1; if (lans < 0) { lc[lc[i]] = -2; rc[lc[i]] = -2; lc[i] = -1; } if (rans < 0) { lc[rc[i]] = -2; rc[rc[i]] = -2; rc[i] = -1; } if (!lans) return rans; if (!rans) return lans; if (lans < 0 && rans < 0) return max(lans,rans); if (lans < 0) return rans; if (rans < 0) return lans; return lans + rans; } signed helper(signed l, signed r, int d){ int sz = r-l+1; a.assign(sz,0); for (int i=l; i<=r; i++) a[i-l] = h[i]; a.push_back(3e9); stack<int> st; st.push(sz); lc.assign(sz+1,-1); rc.assign(sz+1,-1); for (int i=0; i<sz; i++){ int last = -1; while (a[i] > a[st.top()]) { last=st.top(); st.pop(); } lc[i] = last; rc[st.top()]=i; st.push(i); } return dfs(sz,d); } void init(signed N, std::vector<signed> H){ h.resize(N); for (int i = 0; i < N; i++) h[i] = H[i]; } void init0(int d) { helper(0, h.size()-1, d); pr[0] = (lc[0]==-1 && rc[0]==-1); for (int i=1; i<h.size(); i++) pr[i] = pr[i-1] + (lc[i]==-1 && rc[i]==-1); for (int i=0; i<h.size(); i++) if (lc[i]!=-2) usef.push_back(i); for (int i=0; i<usef.size()-1; i++) nxt[usef[i]] = usef[i+1]; for (int i=1; i<usef.size(); i++) prv[usef[i]] = usef[i-1]; } signed max_towers(signed l, signed r, signed d) { if (!inited) init0(d), inited = 1; if (r-l <= 1) return 1; int s = sum(l+1,r-1); s += nxt.count(l) && h[l] < h[nxt[l]] && nxt[l]<=r; s += prv.count(r) && h[r] < h[prv[r]] && prv[r]>=l; return s; }

Compilation message (stderr)

towers.cpp: In function 'long long int dfs(long long int, long long int)':
towers.cpp:36:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   36 |  if (!lans) return rans; if (!rans) return lans;
      |  ^~
towers.cpp:36:26: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   36 |  if (!lans) return rans; if (!rans) return lans;
      |                          ^~
towers.cpp: In function 'void init0(long long int)':
towers.cpp:72:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |  for (int i=1; i<h.size(); i++) pr[i] = pr[i-1] + (lc[i]==-1 && rc[i]==-1);
      |                ~^~~~~~~~~
towers.cpp:73:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |  for (int i=0; i<h.size(); i++) if (lc[i]!=-2) usef.push_back(i);
      |                ~^~~~~~~~~
towers.cpp:74:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |  for (int i=0; i<usef.size()-1; i++) nxt[usef[i]] = usef[i+1];
      |                ~^~~~~~~~~~~~~~
towers.cpp:75:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   75 |  for (int i=1; i<usef.size(); i++) prv[usef[i]] = usef[i-1];
      |                ~^~~~~~~~~~~~
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