洛谷__P1638 逛画展（双指针）

题目链接：P1638 逛画展 - 洛谷

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题目大意：

从m位画家的画作序列中，找长度最短的连续区间[x,y]，包含所有画家。

若有多个，输出x最小的。门票价等于区间长度。

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代码：

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<vector>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<unordered_set>
#include<unordered_map>
#include<bitset>
#include<tuple>
#include<array>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/hash_policy.hpp>
#include <ext/numeric>
#define inf 72340172838076673
#define int long long
#define endl '\n'
#define F first
#define S second
#define mst(a,x) memset(a,x,sizeof (a))
#define pb push_back
#define gmap __gnu_pbds::gp_hash_table
#define power __gnu_cxx::power
using namespace std;
typedef pair<int, int> pii;

const int N = 1000086, mod = 998244353;

int n, m;
int a[N];
gmap<int, int> mp;

void solve() {

    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    
    
    int cnt = 0, mn = inf;
    int x = 0, y = 0;
    
    for (int l = 1, r = 1; r <= n; r++) {
        mp[a[r]]++;
        if (mp[a[r]] == 1) cnt++;
        
        while (cnt == m) {
            if (mn > r - l) {
                x = l, y = r;
                mn = r - l;
            }
            
            mp[a[l]]--;
            if (mp[a[l++]] == 0) cnt--;
        }
        
    }
    
    cout << x << " " << y << endl;
    
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);
    
    int T = 1;
// cin >> T;
    while (T--) solve();
    
    return 0;
}