Submission #1222186

#	Time	Username	Problem	Language	Result	Execution time	Memory
1222186		kargneq	Comparing Plants (IOI20_plants)	C++20	0 / 100	1 ms	328 KiB

plants

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

vector<int> r;
vector<int> prefix;
vector<int> height;
int n, k;
bool built = false;

// Subtask 1: k == 2
void build_prefix() {
    prefix.assign(n + 1, 0);
    for (int i = 0; i < n; ++i)
        prefix[i + 1] = prefix[i] + r[i];
}

// Subtasks 2 & 3: 2k > n
void build_heights() {
    height.assign(n, 0);
    vector<int> rr = r;
    set<int> used;
    for (int h = n; h >= 1; --h) {
        int idx = -1;
        for (int i = 0; i < n; ++i) {
            if (rr[i] == 0 && !used.count(i)) {
                // Check if all previous k-2 are used
                bool ok = true;
                for (int j = 1; j < k; ++j) {
                    int prev = (i - j + n) % n;
                    if (!used.count(prev) && rr[prev] == 0) {
                        ok = false;
                        break;
                    }
                }
                if (ok) {
                    idx = i;
                    break;
                }
            }
        }
        if (idx == -1) break;
        height[idx] = h;
        used.insert(idx);
        for (int j = 1; j < k; ++j) {
            int prev = (idx - j + n) % n;
            if (!used.count(prev))
                rr[prev]--;
        }
    }
    built = true;
}

void init(int kk, std::vector<int> rr) {
    r = rr;
    n = r.size();
    k = kk;
    built = false;
    if (k == 2) build_prefix();
    else if (2 * k > n) build_heights();
}

int compare_plants(int x, int y) {
    if (k == 2) {
        // Subtask 1: Use prefix sums
        int l = (x + 1) % n, r_ = y;
        if (l < r_) {
            if (prefix[r_] - prefix[l] == 0) return 1;
            if (prefix[r_] - prefix[l] == r_ - l) return -1;
        } else {
            int sum = (prefix[n] - prefix[l]) + prefix[r_];
            if (sum == 0) return 1;
            if (sum == (n - l) + r_) return -1;
        }
        return 0;
    } else if (2 * k > n) {
        // Subtasks 2 & 3: Build a possible configuration and compare heights
        if (!built) build_heights();
        if (height[x] > height[y]) return 1;
        if (height[x] < height[y]) return -1;
        return 0;
    }
    // For other cases, not implemented
    return 0;
}

• Subtask 1: 0 / 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