제출 #1249682

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1249682		QwertyPi	3개의 봉우리 (IOI25_triples)	C++20	8 / 100	2095 ms	15888 KiB

triples

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

#define int long long

using namespace std;

const int N_MAX = 2e5 + 11;
int N;
int H[N_MAX];

bool in(int x) {
    return 0 <= x && x < N;
}

bool check(int a, int b, int c) {
    if (!in(a) || !in(b) || !in(c) || a >= b || b >= c) return false;
    return multiset<int>{H[a], H[b], H[c]} == multiset<int>{abs(a - b), abs(a - c), abs(b - c)};
}

set<tuple<int, int, int>> S;
bool check_set(int a, int b, int c) {
    // cout << a << ' ' << b << ' ' << c << endl;
    bool ok = check(a, b, c);
    if (!ok) return false;
    if (S.count({a, b, c})) return false;
    S.insert({a, b, c}); return true;
}

int count_triples(vector<int32_t> H) {
    N = H.size();
    for (int i = 0; i < N; i++) ::H[i] = H[i];

    for (int i = 0; i < N; i++) {
        int a = i;
        {
            int b = a - H[a];
            if (in(b)) {
                int c = b + H[b];
                check_set(b, a, c);
            }
            if (in(b)) {
                int c = a + H[b];
                check_set(b, a, c);
            }
        }

        {
            int b = a + H[a];
            if (in(b)) {
                int c = b - H[b];
                check_set(c, a, b);
            }
            if (in(b)) {
                int c = a - H[b];
                check_set(c, a, b);
            }
        }
    }
    int ans = S.size();

    for (int a = 0; a < N; a++) {
        for (int b = a + 1; b < N; b++) {
            for (int c = b + 1; c < N; c++) {
                if (check(a, b, c) && c - a == H[b]) ans++;
            }
        }
    }
    return ans;
}

vector<int32_t> construct_range(int32_t M, int32_t K) {
    return {1, 1, 1};
}

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