Submission #561403

#	Time	Username	Problem	Language	Result	Execution time	Memory
561403		piOOE	Rainforest Jumps (APIO21_jumps)	C++17	100 / 100	1383 ms	47972 KiB

jumps

#include "jumps.h"

#include <bits/stdc++.h>

using namespace std;

#define all(x) begin(x), end(x)

const int logn = 19, N = 200001;

int h[N], jump[logn][N], R[N], L[N], spt[logn][N], n, jmp[logn][N];
const int infI = 1e9 + 7;


int Min(int i, int j) {
    return h[i] < h[j] ? i : j;
}

int Max(int i, int j) {
    return h[i] > h[j] ? i : j;
}

int get_max(int l, int r) {
    if (r <= l) return -1;
    int sz = __lg(r - l);
    return Max(spt[sz][l], spt[sz][r - (1 << sz)]);
}

void init(int nn, vector<int> H) {
    n = nn;
    for (int i = 0; i < n; ++i) {
        h[i] = H[i];
    }
    vector<int> st;
    for (int i = 0; i < n; ++i) {
        while (!st.empty() && h[st.back()] < h[i]) {
            R[st.back()] = i;
            st.pop_back();
        }
        if (st.empty()) {
            L[i] = -1;
        } else {
            L[i] = st.back();
        }
        st.push_back(i);
    }
    for (int i: st) {
        R[i] = n;
    }
    st.clear();
    for (int i = 0; i < n; ++i) {
        if (R[i] == n)
            jump[0][i] = L[i];
        else if (L[i] == -1)
            jump[0][i] = R[i];
        else
            jump[0][i] = Max(L[i], R[i]);
        jmp[0][i] = R[i];
        spt[0][i] = i;
    }
    jmp[0][n] = n;
    jump[0][n] = -1;
    for (int j = 1; j < logn; ++j) {
        for (int i = 0; i <= n; ++i) {
            if (jump[j - 1][i] != -1)
                jump[j][i] = jump[j - 1][jump[j - 1][i]];
            else
                jump[j][i] = -1;
            jmp[j][i] = jmp[j - 1][jmp[j - 1][i]];
        }
    }
    for (int j = 1; j < logn; ++j) {
        for (int i = 0; i + (1 << j) <= n; ++i) {
            spt[j][i] = Max(spt[j - 1][i], spt[j - 1][i + (1 << (j - 1))]);
        }
    }
}

int minimum_jumps(int A, int B, int C, int D) {
    ++D, ++B;
    int mxcd = get_max(C, D);
    int lx = A - 1, rx = C;
    while (lx + 1 < rx) {
        int m = (lx + rx) >> 1;
        if (h[get_max(m, C)] < h[mxcd]) rx = m;
        else lx = m;
    }
    if (rx >= B) {
        return -1;
    }
    int i = get_max(rx, B);
    int mxx = get_max(i, C);
    for (int j = logn - 1; j > -1; --j) {
        if (C + (1 << j) <= n && h[get_max(C, C + (1 << j))] < h[mxx]) {
            C += (1 << j);
        }
    }
    //now C is the first correct index
    int ans = infI;
    int nw = 0;
    for (int j = logn - 1; j > -1; --j) {
        if (jump[j][i] == -1) continue;
        if (h[jump[j][i]] < h[C]) {
            nw += (1 << j);
            i = jump[j][i];
        }
    }
    if (L[i] != -1 && h[L[i]] >= h[C] && h[L[i]] <= h[mxcd]) {
        ans = min(ans, nw + 2);
        //maybe we can just go one time left and one time right
    }
    for (int j = logn - 1; j > -1; --j) {
        if (jmp[j][i] < C) {
            nw += (1 << j);
            i = jmp[j][i];
        }
    }
    return min(ans, nw + 1);
}

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