Submission #717803

#	Time	Username	Problem	Language	Result	Execution time	Memory
717803		InternetPerson10	Rainforest Jumps (APIO21_jumps)	C++17	56 / 100	1649 ms	52380 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>

using namespace std;

int subtask = 1;

int n;
vector<int> nums, l, r;
vector<array<int, 20>> liftBig, liftRight, liftLeft;

bool invalid(int k) {
    if(k == -1 || k == n) return true;
    return false;
}

int bigger(int a, int b) {
    if(invalid(a) && invalid(b)) return -1;
    if(invalid(a)) return b;
    if(invalid(b)) return a;
    if(nums[a] > nums[b]) return a;
    return b;
}

void init(int N, std::vector<int> H) {
    bool subtask1 = true;
    for(int i = 0; i < N; i++) {
        if(H[i] != i+1) subtask1 = false;
        H[i]--;
    }
    if(subtask1) subtask = 1;
    else if(N <= 200) subtask = 2;
    else subtask = 3;
    n = N;
    nums = H;
    l.resize(n, -1);
    r.resize(n, n);
    liftBig.resize(n, array<int, 20>());
    liftRight.resize(n, array<int, 20>());
    liftLeft.resize(n, array<int, 20>());
    vector<int> v;
    v.push_back(0);
    for(int i = 1; i < n; i++) {
        while(v.size()) {
            if(nums[v.back()] < nums[i]) {
                r[v.back()] = i;
                v.pop_back();
            }
            else break;
        }
        v.push_back(i);
    }
    v.clear();
    v.push_back(n-1);
    for(int i = n-2; i >= 0; i--) {
        while(v.size()) {
            if(nums[v.back()] < nums[i]) {
                l[v.back()] = i;
                v.pop_back();
            }
            else break;
        }
        v.push_back(i);
    }
    for(int j = 0; j < N; j++) {
        liftBig[j][0] = bigger(l[j], r[j]);
        liftLeft[j][0] = l[j];
        if(r[j] == n) liftRight[j][0] = -1;
        else liftRight[j][0] = r[j];
    }
    for(int i = 1; i < 20; i++) {
        for(int j = 0; j < N; j++) {
            if(liftBig[j][i-1] == -1) liftBig[j][i] = -1;
            else liftBig[j][i] = liftBig[liftBig[j][i-1]][i-1];
            if(liftRight[j][i-1] == -1) liftRight[j][i] = -1;
            else liftRight[j][i] = liftRight[liftRight[j][i-1]][i-1];
            if(liftLeft[j][i-1] == -1) liftLeft[j][i] = -1;
            else liftLeft[j][i] = liftLeft[liftLeft[j][i-1]][i-1];
        }
    }
}

int BIG = 1e9 + 7;

int reachable(int x, int C, int D) { // With a series of right jumps
    if(C <= x && x <= D) return 0;
    if(x > D) return -1;
    int ans2 = BIG, tot = 0;
    for(int i = 19; i >= 0; i--) {
        if(liftRight[x][i] == -1) continue;
        if(liftRight[x][i] > D) continue;
        if(liftRight[x][i] >= C) ans2 = min(ans2, tot + (1 << i));
        else {
            x = liftRight[x][i];
            tot += (1 << i);
        }
    }
    if(ans2 == BIG) return -1;
    return ans2;
}

int single_min_jumps(int x, int C, int D) {
    int r = reachable(x, C, D);
    if(r == -1) return BIG;
    int ans = r;
    int tot = 0;
    if(subtask == 2) {
        while(liftBig[x][0] != -1) {
            x = liftBig[x][0];
            tot++;
            r = reachable(x, C, D);
            if(r != -1) ans = min(ans, r + tot);
        }
        return ans;
    }
    for(int i = 19; i >= 0; i--) {
        if(liftBig[x][i] == -1) continue;
        int r = reachable(liftBig[x][i], C, D);
        if(r == -1) continue;
        ans = min(ans, tot + (1 << i) + r);
        if(r != 0) {
            x = liftBig[x][i];
            tot += (1 << i);
        }
    }
    return ans;
}

map<pair<int, pair<int, int>>, int> dp;

int single_min_jumps_brute(int x, int C, int D) {
    if(invalid(x)) return BIG;
    pair<int, pair<int, int>> p = {x, {C, D}};
    if(dp.count(p)) return dp[p];
    if(C <= x && x <= D) return dp[p] = 0;
    return dp[p] = min(single_min_jumps_brute(l[x], C, D),
            single_min_jumps_brute(r[x], C, D)) + 1;
}

void debug(int A, int B, int C, int D, int ans) {
    int ans2 = BIG;
    for(int i = A; i <= B; i++) {
        ans2 = min(ans2, single_min_jumps_brute(i, C, D));
    }
    if(ans2 == BIG) ans2 = -1;
    if(ans != ans2) {
        cerr << "NUMBERS:\n";
        for(int i = 0; i < n; i++) cerr << i << ' ' << nums[i] << '\n';
        cerr << '\n';
        cerr << "CASE: " << A << ' ' << B << ' ' << C << ' ' << D << '\n';
        cerr << "ANS: " << ans << '\n';
        cerr << "BRUTE: " << ans2 << '\n';
        assert(false);
    }
}

int minimum_jumps(int A, int B, int C, int D) {
    int ans = BIG;
    if(C != D) {
        int X = C;
        for(int i = 19; i >= 0; i--) {
            if(liftRight[X][i] == -1) continue;
            if(liftRight[X][i] > D) continue;
            X = liftRight[X][i];
        }
        if(nums[B] > nums[X]) return -1;
        for(int i = 19; i >= 0; i--) {
            if(liftLeft[B][i] == -1) continue;
            if(liftLeft[B][i] < A) continue;
            if(nums[liftLeft[B][i]] > nums[X]) continue;
            B = liftLeft[B][i];
        }
        ans = min(ans, single_min_jumps(B, C, D));
    }
    else {
        for(int i = 19; i >= 0; i--) {
            if(liftLeft[B][i] == -1) continue;
            if(liftLeft[B][i] < A) continue;
            if(reachable(liftLeft[B][i], C, D) == -1) continue;
            B = liftLeft[B][i];
        }
        ans = single_min_jumps(B, C, D);
    }
    if(ans == BIG) ans = -1;
    return ans;
}

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