Submission #921106

#TimeUsernameProblemLanguageResultExecution timeMemory
921106danikoynovShortcut (IOI16_shortcut)C++14
0 / 100
1 ms1368 KiB
#include "shortcut.h" #include <bits/stdc++.h> using namespace std; typedef long long ll; const int maxn = 3010; const ll inf = 1e18; int n; ll cp[maxn], cs[maxn], pref[maxn], bef[maxn], aft[maxn]; ll l[maxn], d[maxn], c; ll dist[maxn]; struct edge { int to; ll w; edge(int _to = 0, ll _w = 0) { to = _to; w = _w; } bool operator < (const edge &e) const { return w > e.w; } }; int used[maxn]; ll get_dist(int l, int r) { if (l > r) swap(l, r); return pref[r - 1] - pref[l - 1]; } const int maxlog = 21; struct sparse_table { ll dp[maxlog][maxn]; int lg[maxn]; void build(vector < ll > values) { int len = values.size(); for (int i = 1; i <= len; i ++) { lg[i] = lg[i / 2] + 1; dp[0][i] = values[i - 1]; } for (int j = 1; j < lg[len]; j ++) { for (int i = 1; i <= len - (1 << j) + 1; i ++) { dp[j][i] = dp[j - 1][i + (1 << (j - 1))]; if (dp[j - 1][i] > dp[j][i]) dp[j][i] = dp[j - 1][i]; } } } ll query(int l, int r) { if (l > r) return 0; int mlog = lg[r - l + 1] - 1; ll ans = dp[mlog][r - (1 << mlog) + 1]; if (dp[mlog][l] > ans) ans = dp[mlog][l]; return ans; } }; ll find_shortcut(int N, vector<int> L, vector<int> D, int C) { n = N; c = C; for (int i = 0; i < n - 1; i ++) l[i + 1] = L[i]; for (int i = 0; i < n; i ++) d[i + 1] = D[i]; for (int i = 1; i <= n; i ++) { pref[i] = pref[i - 1] + l[i]; } for (int i = 1; i <= n; i ++) { cp[i] = cp[i - 1] + l[i - 1]; cp[i] = max(cp[i], d[i]); bef[i] = bef[i - 1]; for (int j = 1; j < i; j ++) { bef[i] = max(bef[i], get_dist(i, j) + d[i] + d[j]); } } for (int i = n; i > 0; i --) { cs[i] = cs[i + 1] + l[i]; cs[i] = max(cs[i], d[i]); aft[i] = aft[i + 1]; for (int j = i + 1; j <= n; j ++) { aft[i] = max(aft[i], get_dist(i, j) + d[i] + d[j]); } } vector < ll > dir_values; for (int i = 1; i <= n; i ++) { dir_values.push_back({pref[i - 1] + d[i]}); } sparse_table direct; direct.build(dir_values); vector < ll > ar_values; for (int i = 1; i <= n; i ++) { ar_values.push_back({-pref[i - 1] + d[i]}); } sparse_table around; around.build(ar_values); ll ans = inf; for (int l = 1; l <= n; l ++) { ll last = inf; for (int r = l + 1; r <= n; r ++) { ll res = max(bef[l], aft[r]), len = pref[r - 1] - pref[l - 1] + c; int rb = l - 1; for (int i = l; i <= r; i ++) { /**int lf = i, rf = r; while(lf <= rf) { int mf = (lf + rf) / 2; if (get_dist(i, mf) <= len - get_dist(i, mf)) lf = mf + 1; else rf = mf - 1; }*/ while(rb < r) { if (get_dist(i, rb + 1) <= len - get_dist(i, rb + 1)) { rb ++; } else break; } if (rb > i) { /**cout << "vergleich " << direct.query(i + 1, rb) << " " << *act.rbegin() << endl; for (int p = i + 1; p <= rb; p ++) cout << dir_values[p - 1] << " "; cout << endl;*/ ll path = direct.query(i + 1, rb) - pref[i - 1] + d[i]; if (i == l) path = path - d[i] + cp[i]; res = max(res, path); if (rb >= r) { path = dir_values[r - 1] - pref[i - 1] + d[i] - d[r] + cs[r]; if (i == l) path = path - d[i] + cp[i]; res = max(res, path); } } /**for (int j = i + 1; j <= rb; j ++) { ll path = get_dist(i, j) + d[i] + d[j]; if (i == l) path = path - d[i] + cp[i]; if (j == r) path = path - d[j] + cs[j]; res = max(res, path); }*/ //cout << "line " << r - i << " " << act.size() + rev.size() << endl; if (rb < r) { ll path = around.query(rb + 1, r) + pref[i - 1] + d[i] + len; if (i == l) path = path - d[i] + cp[i]; res = max(res,path); path = ar_values[r - 1] + pref[i - 1] + d[i] + len - d[r] + cs[r]; if (i == l) path = path - d[i] + cp[i]; res = max(res, path); } /**cout << "line " << res << endl; for (int j = rb + 1; j <= r; j ++) { ll path = len - get_dist(i, j) + d[i] + d[j]; if (i == l) path = path - d[i] + cp[i]; if (j == r) path = path - d[j] + cs[j]; res = max(res, path); } cout << "aft " << res << endl;*/ /**for (int j = i + 1; j <= r; j ++) { ll path = min(len - get_dist(i, j), get_dist(i, j)) + d[i] + d[j]; if (i == l) path = path - d[i] + cp[i]; if (j == r) path = path - d[j] + cs[j]; res = max(res, path); }*/ } if (res == last) break; last = res; ///cout << "range " << l << " " << r << " " ans = min(ans, res); } } return ans; }

Compilation message (stderr)

shortcut.cpp: In function 'll find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:56:35: warning: 'direct.sparse_table::lg[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |         for (int j = 1; j < lg[len]; j ++)
      |                             ~~~~~~^
shortcut.cpp:56:35: warning: 'direct.sparse_table::lg[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
shortcut.cpp:56:35: warning: 'around.sparse_table::lg[<unknown>]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |         for (int j = 1; j < lg[len]; j ++)
      |                             ~~~~~~^
shortcut.cpp:56:35: warning: 'around.sparse_table::lg[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
shortcut.cpp:56:35: warning: 'direct.sparse_table::lg[<unknown>]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |         for (int j = 1; j < lg[len]; j ++)
      |                             ~~~~~~^
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