Submission #646338

#TimeUsernameProblemLanguageResultExecution timeMemory
646338Alex_tz307Peru (RMI20_peru)C++17
100 / 100
106 ms65756 KiB
#include <bits/stdc++.h> #include "peru.h" using namespace std; const int base = 23; const int mod = 1e9 + 7; const int kN = 2e6 + 5e5; const int64_t INF = 1e18L; int a[1 + kN], st[1 + kN], prv[1 + kN], nxt[1 + kN], dqMax[kN], dq[kN], stk[1 + kN]; int64_t dp[1 + kN]; void minSelf(int64_t &x, int64_t y) { if (y < x) { x = y; } } int64_t cost(int index) { return dp[prv[index]] + a[index]; } int add(int x, int y) { x += y; if (x >= mod) { x -= mod; } return x; } int mult(int x, int y) { return (int64_t)x * y % mod; } int solve(int n, int k, int* v) { for (int i = 1; i <= n; ++i) { a[i] = v[i - 1]; } int vf = 0; for (int i = 1; i <= n; ++i) { nxt[i] = n + 1; while (vf && a[st[vf]] <= a[i]) { /// <= nxt[st[vf]] = i; vf -= 1; } prv[i] = st[vf]; st[++vf] = i; } int res = 0, l = 0, r = -1, lmax = 0, rmax = -1; vf = 0; for (int i = 1; i <= n; ++i) { while (vf && a[stk[vf]] <= a[i]) { /// <= vf -= 1; } if (nxt[i] - prv[i] >= k) { while (l <= r && cost(i) <= cost(dq[r])) { r -= 1; } dq[++r] = i; } else if (vf == 0 || cost(i) < cost(stk[vf])) { stk[++vf] = i; } while (l <= r && prv[dq[l]] <= i - k) { l += 1; } while (lmax <= rmax && a[dqMax[rmax]] <= a[i]) { rmax -= 1; } dqMax[++rmax] = i; while (dqMax[lmax] <= i - k) { lmax += 1; } if (i >= k) { dp[i] = dp[i - k] + a[dqMax[lmax]]; } else { dp[i] = a[dqMax[lmax]]; } if (l <= r) { minSelf(dp[i], cost(dq[l])); } if (vf) { minSelf(dp[i], cost(stk[vf])); } res = add(mult(res, base), dp[i] % mod); } return res; }
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