Submission #1252877

#	Time	Username	Problem	Language	Result	Execution time	Memory
1252877		ollelap	Triple Peaks (IOI25_triples)	C++20	17 / 100	188 ms	43044 KiB

triples

#pragma GCC optimize ("O3")

#include "triples.h"

using namespace std;
#include <bits/stdc++.h>
typedef long long ll;
#define rep(i,a,b) for(ll i = a; i < b; i++)

long long count_triples(std::vector<int> arr) {
    int n = arr.size();

    set<tuple<int,int,int>> ans;

    auto check = [&](int i, int j, int k) {
        int ind[] = {i, j, k};
        int a[] = {min(j-i, k-j), max(j-i, k-j), abs(k-i)};
        int b[] = {arr[i], arr[j], arr[k]};
        sort(b, b+3);
        
        if (a[0] == b[0] && a[1] == b[1] && a[2] == b[2]) {
            ans.insert({ind[0], ind[1], ind[2]});
        }
    };

    rep(i,0,n) {
        for (auto j : {i + arr[i], i - arr[i]}) {
            if (j < 0 || j > n-1) continue;
            for (auto k : {i + arr[j], i - arr[j], j + arr[j], j - arr[j]}) {
                if (k < 0 || k > n-1) continue;
                int ind[] = {i, j, k};
                sort(ind, ind+3);
                check(ind[0], ind[1], ind[2]);
            }
        }
    }
    

    vector<vector<int>> forw(2*n), back(2*n);
    vector<int> before(n,0), after(n,0);
    rep(i,0,n) {
        int x = arr[i]-i+n;
        before[i] = forw[x].size();
        forw[x].push_back(i);
    }
    for (int i = n-1; i>= 0; i--) {
        int x = arr[i]+i;
        after[i] = back[x].size();
        back[x].push_back(i);
    }

    rep(b,0,n) {
        if (before[b] < after[b]) {
            rep(i,0,before[b]) {
                int a = forw[arr[b]-b+n][i];
                int c = a + arr[b];
                if (c < n) check(a, b, c);
            }
        }
        else {
            rep(i,0,after[b]) {
                int c = back[arr[b]+b][i];
                int a = c - arr[b];
                if (a > 0) check(a, b, c);
            }
        }
    }
    

    return ans.size();
}

std::vector<int> construct_range(int M, int K) {

    vector<int> res(M);


    
    return res;
}

Compilation message (stderr)

triples.cpp: In function 'long long int count_triples(std::vector<int>)':
triples.cpp:31:30: warning: narrowing conversion of 'i' from 'll' {aka 'long long int'} to 'int' [-Wnarrowing]
   31 |                 int ind[] = {i, j, k};
      |                              ^
triples.cpp:31:33: warning: narrowing conversion of 'j' from 'long long int' to 'int' [-Wnarrowing]
   31 |                 int ind[] = {i, j, k};
      |                                 ^
triples.cpp:31:36: warning: narrowing conversion of 'k' from 'long long int' to 'int' [-Wnarrowing]
   31 |                 int ind[] = {i, j, k};
      |                                    ^

• Subtask 0: 0 / 0
• Subtask 1: 0 / 8
• Subtask 2: 6 / 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