Submission #1030387

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030387		shiomusubi496	Ancient Books (IOI17_books)	C++17	42 / 100	876 ms	1048576 KiB

books

#include "books.h"

#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); --i)

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)

using namespace std;

using ll = long long;

constexpr ll inf = 1e18;

template<class T, class U> bool chmin(T& a, const U& b) { return a > b ? a = b, true : false; }
template<class T, class U> bool chmax(T& a, const U& b) { return a < b ? a = b, true : false; }

template<class M>
class SparseTable {
    using T = typename M::T;
    int n;
    vector<vector<T>> dat;

public:
    SparseTable(vector<T> a) {
        n = a.size();
        int h = __lg(n + 1) + 1;
        dat.assign(h + 1, vector<T>(n, M::id()));
        rep (i, n) dat[0][i] = a[i];
        rep (i, h) rep (j, n - (1 << i)) {
            dat[i + 1][j] = M::op(dat[i][j], dat[i][j + (1 << i)]);
        }
    }
    T prod(int l, int r) const {
        assert(0 <= l && l <= r && r <= n);
        int b = __lg(r - l);
        return M::op(dat[b][l], dat[b][r - (1 << b)]);
    }
};
template<class M>
class SegmentTree {
    using T = typename M::T;
    int n;
    vector<T> dat;

public:
    SegmentTree(vector<T> a) {
        n = 1;
        while (n < a.size()) n <<= 1;
        dat.assign(n << 1, M::id());
        rep (i, a.size()) dat[i + n] = a[i];
        for (int i = n - 1; i >= 1; --i) {
            dat[i] = M::op(dat[i << 1], dat[i << 1 | 1]);
        }
    }
    T prod(int l, int r) const {
        assert(0 <= l && l <= r && r <= n);
        T res1 = M::id(), res2 = M::id();
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l & 1) res1 = M::op(res1, dat[l++]);
            if (r & 1) res2 = M::op(dat[--r], res2);
        }
        return M::op(res1, res2);
    }
    void set(int k, T x) {
        k += n;
        dat[k] = x;
        while (k > 1) {
            k /= 2;
            dat[k] = M::op(dat[k << 1], dat[k << 1 | 1]);
        }
    }
};

struct Min {
    using T = ll;
    static T op(T a, T b) { return min(a, b); }
    static T id() { return inf; }
};
struct Max {
    using T = ll;
    static T op(T a, T b) { return max(a, b); }
    static T id() { return -inf; }
};

long long minimum_walk(std::vector<int> p, int s) {
    int n = p.size();
    if (is_sorted(all(p))) return 0;
    ll ans = 0;
    {
        while (p.back() == n - 1) {
            if (s == n - 1) {
                --s;
                ans += 2;
            }
            p.pop_back();
            --n;
        }
        reverse(all(p));
        rep (i, n) p[i] = n - 1 - p[i];
        s = n - 1 - s;
        while (p.back() == n - 1) {
            if (s == n - 1) {
                --s;
                ans += 2;
            }
            p.pop_back();
            --n;
        }
        reverse(all(p));
        rep (i, n) p[i] = n - 1 - p[i];
        s = n - 1 - s;
    }
    rep (i, n) ans += abs(p[i] - i);
    vector<ll> mns(n), mxs(n);
    {
        vector<bool> seen(n);
        rep (i, n) {
            if (seen[i]) continue;
            int j = i;
            int mx = 0;
            do {
                seen[j] = true;
                chmax(mx, j);
                j = p[j];
            } while (i != j);
            j = i;
            do {
                mns[j] = i;
                mxs[j] = mx;
                j = p[j];
            } while (i != j);
        }
    }
    {
        vector<bool> seen(n, false);
        SegmentTree<Min> seg1(mns);
        SegmentTree<Max> seg2(mxs);
        rep (i, n) {
            if (seen[i]) continue;
            int l = mns[i], r = mxs[i];
            while (1) {
                int l2 = seg1.prod(l, r + 1);
                int r2 = seg2.prod(l, r + 1);
                if (l == l2 && r == r2) break;
                l = l2; r = r2;
            }
            int j = i;
            do {
                seen[j] = true;
                mns[j] = l;
                mxs[j] = r;
                seg1.set(j, l);
                seg2.set(j, r);
                j = p[j];
            } while (i != j);
        }
    }
    SparseTable<Min> st1(mns);
    SparseTable<Max> st2(mxs);

    vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, inf));
    dp[s][s] = 0;
    rep (len, n) {
        rep (l, n + 1 - len) {
            int r = l + len;
            if (dp[l][r] == inf) continue;
            {
                int l2 = st1.prod(l, r + 1);
                int r2 = st2.prod(l, r + 1);
                chmin(dp[l2][r2], dp[l][r]);
            }
            if (l != 0) chmin(dp[mns[l - 1]][max<int>(r, mxs[l - 1])], dp[l][r] + 1);
            if (r != n - 1) chmin(dp[min<int>(l, mns[r + 1])][mxs[r + 1]], dp[l][r] + 1);
        }
    }
    return ans + dp[0][n - 1] * 2;
}

Compilation message (stderr)

books.cpp: In instantiation of 'SegmentTree<M>::SegmentTree(std::vector<typename M::T>) [with M = Min; typename M::T = long long int]':
books.cpp:141:34:   required from here
books.cpp:53:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |         while (n < a.size()) n <<= 1;
      |                ~~^~~~~~~~~~
books.cpp: In instantiation of 'SegmentTree<M>::SegmentTree(std::vector<typename M::T>) [with M = Max; typename M::T = long long int]':
books.cpp:142:34:   required from here
books.cpp:53:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 0 / 28
• Subtask 4: 20 / 20
• Subtask 5: 0 / 30