Submission #1262397

#	Time	Username	Problem	Language	Result	Execution time	Memory
1262397		Canuc80k	Triple Peaks (IOI25_triples)	C++20	11 / 100	218 ms	62592 KiB

triples

#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;

ll res = 0;

void add(ll i, ll j, ll k) {res ++;}

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

ll count(const vector<int>& a, const vector<int>& b) {
    if (a.size() != b.size()) throw invalid_argument("a and b must have same size");
    int n = (int)a.size();
    if (n == 0) return 0;

    map<pair<int,int>, int> cntPair;
    map<int,int> cntA, cntB, diag;
    for (int i = 0; i < n; ++i) {
        cntPair[{a[i], b[i]}]++;
        cntA[a[i]]++;
        cntB[b[i]]++;
    }
    for (auto &it : cntPair) {
        int x = it.first.first;
        int y = it.first.second;
        if (x == y) diag[x] = it.second;
    }

    map<int, vector<pair<int,int>>> listA;
    for (auto &it : cntPair) {
        int x = it.first.first;
        int y = it.first.second;
        int f = it.second;
        listA[x].push_back({y, f});
    }

    auto getCnt = [&](int x, int v)->int {
        auto it = cntPair.find({x, v});
        if (it == cntPair.end()) return 0;
        return it->second;
    };

    ll S_total = 0;
    for (auto &it : cntPair) {
        int x = it.first.first;
        int y = it.first.second;
        int f_xy = it.second;
        ll dot = 0;
        auto &Lx = listA[x];
        auto &Ly = listA[y];
        if (Lx.size() <= Ly.size()) {
            for (auto &p : Lx) {
                int v = p.first;
                int cxv = p.second;
                int cyv = getCnt(y, v);
                if (cyv) dot += (ll)cxv * cyv;
            }
        } else {
            for (auto &p : Ly) {
                int v = p.first;
                int cyv = p.second;
                int cxv = getCnt(x, v);
                if (cxv) dot += (ll)cxv * cyv;
            }
        }
        S_total += (ll)f_xy * dot;
    }

    ll A = 0;
    for (auto &it : cntA) {
        int x = it.first;
        ll cntax = it.second;
        ll d = diag.count(x) ? diag[x] : 0;
        A += cntax * d;
    }

    ll B = 0;
    for (auto &it : diag) {
        ll d = it.second;
        B += d * d;
    }

    ll C = 0;
    for (auto &it : cntB) {
        int x = it.first;
        ll cntbx = it.second;
        ll d = diag.count(x) ? diag[x] : 0;
        C += cntbx * d;
    }

    ll C1 = 0;
    for (auto &it : diag) C1 += it.second;

    ll non_distinct = A + B + C - 2 * C1;
    ll result = S_total - non_distinct;
    return result;
}

long long count_triples(std::vector<int> H) {
    // #TH: a[k] max
    for (int k = 2; k < H.size(); k ++) {
        int i = k - H[k]; if (i < 0 || H[i] >= H[k]) continue; int j1 = k - H[i], j2 = i + H[i];
        if (j1 < 0 || H[j1] >= H[k] || H[j1] != j1 - i) j1 = -1;
        if (j2 >= k || H[j2] >= H[k] || H[j2] != k - j2) j2 = -1;
        if (j1 != -1) add(i, j1, k); if (j2 != -1 && j1 != j2) add(i, j2, k);
    }

    // #TH: a[i] max
    for (int i = 0; i + 2 < H.size(); i ++) {
        int k = i + H[i]; if (k >= H.size() || H[k] >= H[i]) continue; int j1 = k - H[k], j2 = i + H[k];
        if (j1 < 0 || H[j1] >= H[i] || H[j1] != j1 - i) j1 = -1;
        if (j2 >= k || H[j2] >= H[i] || H[j2] != k - j2) j2 = -1;
        if (j1 != -1) add(i, j1, k); if (j2 != -1 && j1 != j2) add(i, j2, k);
    }
    
    // #TH: a[j] max, j - i = a[i]
    for (int i = 0; i + 2 < H.size(); i ++) {
        int j = i + H[i]; if (j >= H.size() || H[j] <= H[i]) continue; int k = i + H[j];
        if (k >= H.size() || H[k] >= H[j] || k - H[k] != j || k - j == H[i]) k = -1;
        if (k != -1) add(i, j, k);
    }

    // #TH: a[j] max, j - i = a[k]
    vector<int> a, b;
    for (int i = 0; i < H.size(); i ++) a.push_back(H[i] + i);
    for (int i = 0; i < H.size(); i ++) b.push_back(H[i] - i);
    res += count(a, b);
    return res;
}

std::vector<int> construct_range(int M, int K) {
    // vector<int> res; res.push_back(1);
    // for (int i = 1; i < M; i ++) res.push_back(i);
    // return res;
}

Compilation message (stderr)

triples.cpp: In function 'std::vector<int> construct_range(int, int)':
triples.cpp:139:1: warning: no return statement in function returning non-void [-Wreturn-type]
  139 | }
      | ^

• Subtask 0: 0 / 0
• Subtask 1: 0 / 8
• Subtask 2: 0 / 6
• Subtask 3: 0 / 10
• Subtask 4: 11 / 11
• Subtask 5: 0 / 16
• Subtask 6: 0 / 19
• Subtask 7: 0 / 5
• Subtask 8: 0 / 5
• Subtask 9: 0 / 5
• Subtask 10: 0 / 5
• Subtask 11: 0 / 5
• Subtask 12: 0 / 5