Submission #1211449

#	Time	Username	Problem	Language	Result	Execution time	Memory
1211449		fafnir	Comparing Plants (IOI20_plants)	C++20	5 / 100	47 ms	6600 KiB

plants

#include <bits/stdc++.h>

// #define LOCAL

using namespace std;

const int NMAX = 200'001;
const int INF = NMAX+1;

int n,k,q;
int r[NMAX+1];
int h[NMAX+1];        // heights or INF if non-existing

// Sum of r[l...r] = rpref[r+1] - rpref[l]
int rpref[NMAX+1];

void init(int kl, vector<int> rl) {
    n = rl.size();
    k = kl;
    for (int i = 0; i < n; ++i) {
        r[i] = rl[i];
        h[i] = 1;
    }
    rpref[0] = 0;
    for (int i = 1; i <= n; ++i) {
        rpref[i] += rpref[i-1];
        rpref[i] += r[i-1];
    }

    if (2*k > n) {
        // Subtask 2
        int curr = n-1;
        unordered_set<int> taken;
        for (int _ = 0; _ < n-1; ++_) {
            
            int prev = 0;
            for (int i = n-1; i >= n-1-(k-1)+1; --i) {
                prev += r[i] > 0;
            }
            
            int j = n-1-(k-1)+1;
            int pos = -1;
            for (int i = 0; i < n; ++i) {
                if (taken.count(i)) continue;
                if (r[i] == 0 && prev > 0) {pos = i; taken.insert(pos); break;} 
                
                prev += r[i] > 0;
                prev -= r[j] > 0;

                j = (j+1) % n;
            }

            // assert (pos != -1);
            h[pos] = (n-_);

            int cnt = k-1;
            while (cnt >= 0) {
                int t = (pos-cnt);
                if (t < 0) t += n;
                r[t]--;
                cnt--;
            }
        }

    }
}

bool taller(int x, int y) {
    // Condition 1
    // r[x...y-1] all 0  --> From x to y, all are smaller than x
    int c0 = rpref[y] - rpref[x];
    if (c0 == 0) return true;

    // Condition 2
    // r[y...n-1] & r[0...x-1] = 1 --> From y ... x, all are larger than y
    int c1 = 0;
    int l1 = 0;
    c1 += rpref[n] - rpref[y];
    l1 += n-1-y+1;


    if (x > 0) {
        c1 += rpref[x] - rpref[0];
        l1 += x-1-0+1;
    }

    if (l1 == c1) return true;
    return false;
}

bool smaller(int x, int y) {
    // Condition 1
    // r[x...y-1] all 1 --> all larger than x
    int c0 = rpref[y] - rpref[x];
    if (c0 == (y-1-x+1)) return true;

    int c1 = 0;
    c1 += rpref[n] - rpref[y];

    if (x > 0) {
        c1 += rpref[x] - rpref[0];
    }

    return c1 == 0;
}

// x, y: Labels of plants
//  Return:
//      1:   x taller than plant y
//     -1:   x smaller than plant y
//      0:   inconclusive
int compare_plants(int x, int y) {

    // Subtask 1
    if (k == 2) {
        if (taller(x, y)) { return 1; } 
        else if (smaller(x, y)) { return -1; } 
        else { return 0; }
    } else if (2*k > n) {
        if (h[x] > h[y]) return 1;
        else if (h[x] < h[y]) return -1;
        
        return 0;    
    }

    return -1;
}

#ifdef LOCAL

int32_t main() {

    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int nl, kl, ql;
    cin >> nl >> kl >> ql;

    vector<int> rl(nl);
    for (auto& e : rl) cin >> e;

    init(kl, rl);

    for (int _ = 0; _ < ql; _++) {
        int x, y;
        cin >> x >> y;
        cout << compare_plants(x, y);
        if (_ < ql-1) cout << '\n';
    }

    return 0;
}

#endif

• Subtask 1: 5 / 5
• Subtask 2: 0 / 14
• Subtask 3: 0 / 13
• Subtask 4: 0 / 17
• Subtask 5: 0 / 11
• Subtask 6: 0 / 15
• Subtask 7: 0 / 25