Submission #650058

#	Time	Username	Problem	Language	Result	Execution time	Memory
650058		phathnv	Rainforest Jumps (APIO21_jumps)	C++11	100 / 100	1532 ms	63816 KiB

jumps

#include <bits/stdc++.h>

using namespace std;

const int LOGN = 18;

int n;
vector<int> h;
vector<vector<int>> l, r, best;

void init(int _n, vector<int> _h) {
    n = _n;
    h = _h;

    l.assign(n, vector<int>(LOGN, 0));
    r.assign(n, vector<int>(LOGN, 0));
    best.assign(n, vector<int>(LOGN, 0));

    l[0][0] = -1;
    for (int i = 1; i < n; ++i) {
        l[i][0] = i - 1;
        while (l[i][0] != -1 && h[i] > h[l[i][0]]) {
            l[i][0] = l[l[i][0]][0];
        }
    }
    r[n - 1][0] = -1;
    for (int i = n - 2; i >= 0; --i) {
        r[i][0] = i + 1;
        while (r[i][0] != -1 && h[i] > h[r[i][0]]) {
            r[i][0] = r[r[i][0]][0];
        }
    }
    for (int i = 0; i < n; ++i) {
        if (l[i][0] == -1 || r[i][0] == -1) {
            best[i][0] = max(l[i][0], r[i][0]);
        } else if (h[l[i][0]] > h[r[i][0]]) {
            best[i][0] = l[i][0];
        } else {
            best[i][0] = r[i][0];
        }
    }

    for (int i = 0; i < n; ++i) {
        for (int j = 1; j < LOGN; ++j) {
            l[i][j] = (l[i][j - 1] == -1? -1 : l[l[i][j - 1]][j - 1]);
        }
    }
    for (int i = n - 1; i >= 0; --i) {
        for (int j = 1; j < LOGN; ++j) {
            r[i][j] = (r[i][j - 1] == -1? -1 : r[r[i][j - 1]][j - 1]);
        }
    }
    for (int j = 1; j < LOGN; ++j) {
        for (int i = 0; i < n; ++i) {
            best[i][j] = (best[i][j - 1] == -1? -1 : best[best[i][j - 1]][j - 1]);
        }
    }
}

int getMax(int u, int v) {
    if (u > v) {
        return 0;
    }
    int p = u;
    for (int i = LOGN - 1; i >= 0; --i) {
        if (r[p][i] != -1 && r[p][i] <= v) {
            p = r[p][i];
        }
    }
    return h[p];
}

int minimum_jumps(int a, int b, int c, int d) {
    int maxR = getMax(c, d);
    int maxC = getMax(b + 1, c - 1);

    int s = b;

    // find optimal s
    for (int i = LOGN - 1; i >= 0; --i) {
        if (l[s][i] != -1 && l[s][i] >= a && h[l[s][i]] < maxR) {
            s = l[s][i];
        }
    }

    int res = 0;
    for (int i = LOGN - 1; i >= 0; --i) {
        if (best[s][i] != -1 && h[best[s][i]] < maxC) {
            res += (1 << i);
            s = best[s][i];
        }
    }

    // r
    if (c <= r[s][0] && r[s][0] <= d) {
        return res + 1;
    }

    // l-r
    if (l[s][0] != -1 && c <= r[l[s][0]][0] && r[l[s][0]][0] <= d) {
        return res + 2;
    }

    // r-r-r...
    for (int i = LOGN - 1; i >= 0; --i) {
        if (r[s][i] != -1 && h[r[s][i]] <= maxC) {
            res += (1 << i);
            s = r[s][i];
        }
    }
    if (c <= r[s][0] && r[s][0] <= d) {
        return res + 1;
    }

    return -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