Submission #1342249

#	Time	Username	Problem	Language	Result	Execution time	Memory
1342249		tutithuybi123	Triple Peaks (IOI25_triples)	C++20	Compilation error	0 ms	0 KiB

triples

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

long long count_triples(vector<int> H) {
    int N = (int)H.size();
    long long ans = 0;

    vector<vector<int>> L(N), R(N);

    // Build L[j] = lengths x such that H[j-x] = x
    // and R[j] = lengths y such that H[j+y] = y
    for (int p = 0; p < N; ++p) {
        int h = H[p];
        if (p + h < N) L[p + h].push_back(h);
        if (p - h >= 0) R[p - h].push_back(h);
    }

    // Case 1: largest value is at k
    for (int k = 0; k < N; ++k) {
        int s = H[k];
        int i = k - s;
        if (i < 0) continue;

        int a = H[i];
        if (a <= 0 || a >= s) continue;

        int need = s - a;

        int j1 = i + a;
        if (i < j1 && j1 < k && H[j1] == need) {
            ans++;
        }

        int j2 = k - a;
        if (j2 != j1 && i < j2 && j2 < k && H[j2] == need) {
            ans++;
        }
    }

    // Case 2: largest value is at i
    for (int i = 0; i < N; ++i) {
        int s = H[i];
        int k = i + s;
        if (k >= N) continue;

        int a = H[k];
        if (a <= 0 || a >= s) continue;

        int need = s - a;

        int j1 = i + a;
        if (i < j1 && j1 < k && H[j1] == need) {
            ans++;
        }

        int j2 = k - a;
        if (j2 != j1 && i < j2 && j2 < k && H[j2] == need) {
            ans++;
        }
    }

    // Case 3: largest value is at j
    for (int j = 0; j < N; ++j) {
        int s = H[j];
        if (L[j].empty() || R[j].empty()) continue;

        if (L[j].size() <= R[j].size()) {
            unordered_set<int> have;
            have.reserve(R[j].size() * 2 + 1);
            for (int y : R[j]) have.insert(y);

            for (int x : L[j]) {
                int y = s - x;
                if (y > 0 && have.find(y) != have.end()) {
                    ans++;
                }
            }
        } else {
            unordered_set<int> have;
            have.reserve(L[j].size() * 2 + 1);
            for (int x : L[j]) have.insert(x);

            for (int y : R[j]) {
                int x = s - y;
                if (x > 0 && have.find(x) != have.end()) {
                    ans++;
                }
            }
        }
    }

    return ans;
}

Compilation message (stderr)

/usr/bin/ld: /tmp/ccfDE2qJ.o: in function `main':
grader.cpp:(.text.startup+0x197): undefined reference to `construct_range(int, int)'
collect2: error: ld returned 1 exit status