题目描述

更易理解的双指针

样例

#include <iostream>
#include <vector>

using namespace std;

int main() {
    int n, m;
    vector<int> balls;
    cin >> n >> m;
    for (int i = 0; i < n; i ++) {
        int k;
        cin >> k;
        balls.push_back(k);
    }
    int s[2001] = {0};

    int l = 0, r = -1;
    int cnt = 0;
    int minLen = n + 1;

    while (l < n) {
        if (r + 1 < n && cnt < m) {
            s[balls[r + 1]] ++;

            if (s[balls[r + 1]] <= 1 && balls[r + 1] != 0) {
                cnt ++;
            }
            r ++;
        } else {
            if (cnt == m && r - l + 1 < minLen) {
                minLen = r - l + 1;
            }
            s[balls[l]] --;
            if (s[balls[l]] < 1 && balls[l] != 0) {
                cnt --;
            }
            l ++;
        }
    }
    if (minLen == n + 1) {
        cout << "-1" << endl;
    } else {
        cout << minLen << endl;   
    }
    return 0;

}