Submission #1095832

#TimeUsernameProblemLanguageResultExecution timeMemory
1095832SalihSahinFlooding Wall (BOI24_wall)C++14
12 / 100
132 ms64960 KiB
#include <bits/stdc++.h> #define pb push_back #define int long long using namespace std; const int N = 2e5 + 5; const int K = 20; const int mod = 1e9 + 7; int32_t main(){ ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); int n; cin>>n; set<int> dfvals; map<int, int> cnt; vector<int> a(n), b(n); for(int i = 0; i < n; i++){ cin>>a[i]; cnt[a[i]]++; if(cnt[a[i]] > 1) dfvals.insert(a[i]); } for(int i = 0; i < n; i++){ cin>>b[i]; cnt[b[i]]++; if(cnt[b[i]] > 1) dfvals.insert(b[i]); } int ans = 0; vector<vector<int> > pre(n+1, vector<int>(3)), suf(n+1, vector<int>(3)); // 0 => max < itr, 1 => max = itr, 2 => max > itr for(auto itr: dfvals){ pre[0][0] = 1; pre[0][1] = pre[0][2] = 0; for(int i = 0; i < n; i++){ pre[i+1][0] = pre[i+1][1] = pre[i+1][2] = 0; if(a[i] < itr){ pre[i+1][0] += pre[i][0]; pre[i+1][1] += pre[i][1]; pre[i+1][2] += pre[i][2]; } else if(a[i] == itr){ pre[i+1][1] += pre[i][0]; pre[i+1][1] += pre[i][1]; pre[i+1][2] += pre[i][2]; } else{ pre[i+1][2] += (pre[i][0] + pre[i][1] + pre[i][2]); } for(int j = 0; j < 3; j++) pre[i+1][j] %= mod; if(b[i] < itr){ pre[i+1][0] += pre[i][0]; pre[i+1][1] += pre[i][1]; pre[i+1][2] += pre[i][2]; } else if(b[i] == itr){ pre[i+1][1] += (pre[i][0] + pre[i][1]); pre[i+1][2] += pre[i][2]; } else{ pre[i+1][2] += (pre[i][0] + pre[i][1] + pre[i][2]); } for(int j = 0; j < 3; j++) pre[i+1][j] %= mod; } suf[n][0] = 1; suf[n][1] = suf[n][2] = 0; for(int i = n-1; i >= 0; i--){ suf[i][0] = suf[i][1] = suf[i][2] = 0; if(a[i] < itr){ suf[i][0] += suf[i+1][0]; suf[i][1] += suf[i+1][1]; suf[i][2] += suf[i+1][2]; } else if(a[i] == itr){ suf[i][1] += suf[i+1][0]; suf[i][1] += suf[i+1][1]; suf[i][2] += suf[i+1][2]; } else{ suf[i][2] += (suf[i+1][0] + suf[i+1][1] + suf[i+1][2]); } for(int j = 0; j < 3; j++) suf[i][j] %= mod; if(b[i] < itr){ suf[i][0] += suf[i+1][0]; suf[i][1] += suf[i+1][1]; suf[i][2] += suf[i+1][2]; } else if(b[i] == itr){ suf[i][1] += suf[i+1][0]; suf[i][1] += suf[i+1][1]; suf[i][2] += suf[i+1][2]; } else{ suf[i][2] += (suf[i+1][0] + suf[i+1][1] + suf[i+1][2]); } for(int j = 0; j < 3; j++) suf[i][j] %= mod; } int add = 0; for(int i = 1; i < n-1; i++){ int calc = (pre[i][1] * suf[i+1][1] + pre[i][2] * suf[i+1][1] + pre[i][1] * suf[i+1][2])%mod; int tot = max(0LL, itr - a[i]) + max(0LL, itr - b[i]); add = (add + (calc * tot)%mod)%mod; } ans = (ans + add)%mod; } cout<<ans<<endl; return 0; }
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