Breed Proximity

题目描述

Farmer John's N cows (\(1 \leq N \leq 50,000\)) are standing in a line, each described by an integer breed ID.
Cows of the same breed are at risk for getting into an argument with each-other if they are standing too close. Specifically, two cows of the same breed are said to be "crowded" if their positions within the line differ by no more than K (\(1 \leq K < N\)).
Please compute the maximum breed ID of a pair of crowded cows.

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6+5;
vector<int> ve[maxn];
int main() {
    //freopen("input.txt","r",stdin);
    int n, k; cin >> n >> k;
    for (int i = 1; i <= n; ++i) {
        int id; cin >> id;
        ve[id].push_back(i);
    }
    int ans = -1;
    for (int i = 0; i <= 1000000; ++i) {
        if (ve[i].size() == 0 || ve[i].size() == 1) continue;
        int pos1 = ve[i][0];
        for (int j = 1; j < ve[i].size(); ++j) {
            int pos2 = ve[i][j];
            if (pos2-pos1 <= k) {
                ans = i;
                break;
            }
            pos1 = pos2;
        }
    }
    cout << ans << endl;
    return 0;
}