Submission #951262

#	Time	Username	Problem	Language	Result	Execution time	Memory
951262		Nhoksocqt1	Rainforest Jumps (APIO21_jumps)	C++17	16 / 100	654 ms	55556 KiB

jumps

#include<bits/stdc++.h>
using namespace std;

#define inf 0x3f3f3f3f
#define sz(x) int((x).size())
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> ii;

template<class X, class Y>
	inline bool maximize(X &x, const Y &y) {return (x < y ? x = y, 1 : 0);}
template<class X, class Y>
	inline bool minimize(X &x, const Y &y) {return (x > y ? x = y, 1 : 0);}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Random(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

const int MAXN = 200005;

int P[MAXN][18], Pi[MAXN][18], Pa[MAXN][18];
int h[MAXN], dist[MAXN], nxt[MAXN], prv[MAXN], nArr;
bool check_sub1;

void init(int _N, vector<int> _H) {
    nArr = _N;

    check_sub1 = 1;
    for (int i = 1; i <= nArr; ++i) {
        h[i] = _H[i - 1];
        check_sub1 &= (i == 1 || h[i] > h[i - 1]);
    }

    stack<int> st;
    for (int i = 1; i <= nArr; ++i) {
        while(sz(st) && h[st.top()] <= h[i])
            st.pop();

        prv[i] = (sz(st)) ? st.top() : 0;
        st.push(i);
    }

    while(sz(st))
        st.pop();

    for (int i = nArr; i > 0; --i) {
        while(sz(st) && h[st.top()] <= h[i])
            st.pop();

        nxt[i] = (sz(st)) ? st.top() : nArr + 1;
        st.push(i);
    }

    for (int i = 1; i <= nArr; ++i) {
        Pi[i][0] = Pa[i][0] = h[i];
        P[i][0] = (h[nxt[i]] >= h[prv[i]]) ? nxt[i] : prv[i];
    }

    P[0][0] = 0, P[nArr + 1][0] = nArr + 1;
    for (int j = 1; (1 << j) <= nArr; ++j) {
        for (int i = 0; i <= nArr + 1; ++i) {
            P[i][j] = P[P[i][j - 1]][j - 1];
            if(i + (1 << j) -  1 <= nArr) {
                Pi[i][j] = min(Pi[i][j - 1], Pi[i + (1 << (j - 1))][j - 1]);
                Pa[i][j] = max(Pa[i][j - 1], Pa[i + (1 << (j - 1))][j - 1]);
            }
        }
    }
}

int brute(int a, int b, int c, int d) {
    for (int i = 1; i <= nArr; ++i)
        dist[i] = -1;

    queue<int> qu;
    for (int i = a; i <= b; ++i) {
        qu.push(i);
        dist[i] = 0;
    }

    while(sz(qu)) {
        int u(qu.front()); qu.pop();

        if(u >= c && u <= d)
            return dist[u];

        if(prv[u] > 0 && dist[prv[u]] < 0) {
            dist[prv[u]] = dist[u] + 1;
            qu.push(prv[u]);
        }

        if(nxt[u] <= nArr && dist[nxt[u]] < 0) {
            dist[nxt[u]] = dist[u] + 1;
            qu.push(nxt[u]);
        }
    }

    return -1;
}

inline int getMin(int l, int r) {
    int log = 31 - __builtin_clz(r - l + 1);
    return min(Pi[l][log], Pi[r - (1 << log) + 1][log]);
}

inline int getMax(int l, int r) {
    int log = 31 - __builtin_clz(r - l + 1);
    return max(Pa[l][log], Pa[r - (1 << log) + 1][log]);
}

int sub5(int a, int c) {
    int res(0);
    for (int i = 31 - __builtin_clz(nArr); i >= 0; --i) {
        if(P[a][i] != 0 && P[a][i] != nArr + 1 && h[P[a][i]] < h[c]) {
            a = P[a][i];
            res += (1 << i);
        }
    }

    if(h[a] < h[c]) {
        a = nxt[a];
        assert(a == c);
        ++res;
    }

    return res;
}

int minimum_jumps(int a, int b, int c, int d) {
    ++a, ++b, ++c, ++d;
    if(check_sub1)
        return c - b;

    int minStart = getMin(a, b), maxBetween(-1), maxEnd = getMax(c, d);
    if(b + 1 <= c - 1)
        maxBetween = getMax(b + 1, c - 1);

    if(minStart >= maxEnd || maxBetween >= maxEnd)
        return -1;

    if(a == b && c == d)
        return sub5(a, c);

    return brute(a, b, c, d);
}

#ifdef Nhoksocqt1

int main(void) {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    #define TASK "jumps"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    vector<int> h;
    int n, q;
    cin >> n >> q;

    h.resize(n);
    for (int i = 0; i < n; ++i)
        cin >> h[i];

    init(n, h);
    for (int t = 0; t < q; ++t) {
        int a, b, c, d;
        cin >> a >> b >> c >> d;
        cout << "ANSWER " << a << ' ' << b << ' ' << c << ' ' << d << ": " << minimum_jumps(a, b, c, d) << '\n';
    }

    return 0;
}

#endif // Nhoksocqt1

• Subtask 1: 4 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 12 / 12
• Subtask 5: 0 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19