Submission #444023

#TimeUsernameProblemLanguageResultExecution timeMemory
444023yungyaoThe Collection Game (BOI21_swaps)C++17
Compilation error
0 ms0 KiB
using namespace std; #include <iostream> #include <algorithm> #include <queue> #include <stack> #include <map> #include <set> #include <utility> #include <vector> #include <memory.h> typedef long long LL; typedef pair<int,int> pii; #define F first #define S second #define mkp make_pair #define iter(x) x.begin(),x.end() #define MEM(s,e) memset(s,e,sizeof(s)) const int maxn = 1e5+100,inf = 1e9; int dp[maxn][2][2]; //index, t/f, on/off bool status[maxn]; vector <int> adj[maxn]; void dfs(int x,int fr){ int ldp[2][2][2],c=0; for (auto s:adj[x]) if (s != fr){ dfs(s,x); for (int i=0;i<2;++i) for (int j=0;j<2;++j){ ldp[c][i][j] = dp[s][i][j]; } ++c; } if (!c){ if (status[x]){ dp[x][1][0] = 0; dp[x][0][1] = 1; dp[x][0][0] = inf; dp[x][1][1] = inf; } else{ dp[x][0][0] = 0; dp[x][1][1] = 1; dp[x][1][0] = inf; dp[x][0][1] = inf; } } else if (c == 1){ if (status[x]){ dp[x][0][0] = ldp[0][0][1]; dp[x][0][1] = ldp[0][1][0] + 1; dp[x][1][0] = ldp[0][0][0]; dp[x][1][1] = ldp[0][1][1] + 1; } else{ dp[x][0][0] = ldp[0][0][0]; dp[x][0][1] = ldp[0][1][1] + 1; dp[x][1][0] = ldp[0][0][1]; dp[x][1][1] = ldp[0][1][0] + 1; } } else{ if (status[x]){ dp[x][0][0] = min(inf,min(ldp[0][0][1] + ldp[1][0][0],ldp[0][0][0] + ldp[1][0][1])); dp[x][0][1] = min(inf,min(ldp[0][1][0] + ldp[1][1][0],ldp[0][1][1] + ldp[1][1][1]) + 1); dp[x][1][0] = min(inf,min(ldp[0][0][0] + ldp[1][0][0],ldp[0][0][1] + ldp[1][0][1])); dp[x][1][1] = min(inf,min(ldp[0][1][1] + ldp[1][1][0],ldp[0][1][0] + ldp[1][1][1]) + 1); } else{ dp[x][0][0] = min(inf,min(ldp[0][0][0] + ldp[1][0][0],ldp[0][0][1] + ldp[1][0][1])); dp[x][0][1] = min(inf,min(ldp[0][1][1] + ldp[1][1][0],ldp[0][1][0] + ldp[1][1][1]) + 1); dp[x][1][0] = min(inf,min(ldp[0][0][1] + ldp[1][0][0],ldp[0][0][0] + ldp[1][0][1])); dp[x][1][1] = min(inf,min(ldp[0][1][0] + ldp[1][1][0],ldp[0][1][1] + ldp[1][1][1]) + 1); } } } int n,mxsub[maxn]; int findg(int x,int fr){ int cnt = 1; for (auto i:adj[x]) if (i != fr){ int r = findg(i,x); cnt += r; mxsub[x] = max(mxsub[x],r); } mxsub[x] = max(mxsub[x],n - cnt); return cnt; } vector <int> findans(int g,int op){ vector <int> hadj[22]; int c=0; vector <int> ret(4,inf); //00 for f/off, 01 for f/on, 10 for t/off, 11 for t/on bool vis[44]{}; int trs[44]{},invtrs[22]{}; queue <int> bfs; bfs.push(g); vis[g] = true; while (bfs.size()){ int x = bfs.front(); bfs.pop(); invtrs[c] = x; trs[x] = c++; for (auto i:adj[x]){ if (vis[i]){ hadj[trs[x]].push_back(trs[i]); hadj[trs[i]].push_back(trs[x]); } else if (i != op){ bfs.push(i); vis[i] = true; } } } for (int mask=0;mask<(1 << c);++mask){ bool stat_copy[22]; for (int i=0;i<c;++i) stat_copy[i] = status[invtrs[i]]; for (int i=0;i<c;++i) if (mask & (1 << i)){ stat_copy[i] ^= 1; for (auto cn:hadj[i]) stat_copy[cn] ^= 1; } bool ok = true; for (int i=1;i<c;++i) if (stat_copy[i]){ok = false; break;} if (ok){ if (stat_copy[0] and (mask & 1)) ret[3] = min(ret[3],__builtin_popcount(mask)); else if (stat_copy[0] and !(mask & 1)) ret[2] = min(ret[2],__builtin_popcount(mask)); else if (!stat_copy[0] and (mask & 1)) ret[1] = min(ret[1],__builtin_popcount(mask)); else if (!stat_copy[0] and !(mask & 1)) ret[0] = min(ret[0],__builtin_popcount(mask)); } } return ret; } void brutesolve(){ findg(1,0); int g[2],c = 0; for (int i=1;i<=n;++i) if (mxsub[i] <= n/2) g[c++] = i; if (c == 1) g[1] = adj[g[0]][0]; vector <int> v1 = findans(g[0],g[1]), v2 = findans(g[1],g[0]); int ans = min(min(v1[0]+v2[0],v1[3]+v2[3]),min(v1[1]+v2[2],v1[2]+v2[1])); if (ans >= inf) cout << "impossible\n"; else cout << ans << '\n'; } int main(){ cin >> n; for (int _=n-1;_--;){ int u,v; cin >> u >> v; adj[u].push_back(v); adj[v].push_back(u); } for (int i=1;i<=n;++i) cin >> status[i]; if (n <= 40) {brutesolve(); return 0;} for (int i=1;i<=n;++i) if (adj[i].size() == 1){ dfs(i,0); int ans = min(dp[i][0][0],dp[i][0][1]); if (ans >= inf) cout << "impossible\n"; else cout << ans << '\n'; break; } return 0; }

Compilation message (stderr)

swaps.cpp: In function 'void brutesolve()':
swaps.cpp:142:40: warning: 'g[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
  142 |     vector <int> v1 = findans(g[0],g[1]), v2 = findans(g[1],g[0]);
      |                                        ^
swaps.cpp:142:40: warning: 'g[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
/usr/bin/ld: /tmp/ccc6fwXw.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cc2WfytA.o:swaps.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccc6fwXw.o: in function `main':
grader.cpp:(.text.startup+0x67): undefined reference to `solve(int, int)'
collect2: error: ld returned 1 exit status