题解 | 【模板】双指针

#include <bits/stdc++.h>
using namespace std;
class QuJ {
  public:
    int x, y;
    QuJ() {
        x = 0;
        y = 0;
    }
};
int main() {
    int n;
    cin >> n;
    int* a = new int [n];
    int* map = new int [n + 1];
    int* index = new int [n];
    int length = 0;
    int count = 0;
    for (int i = 0; i < n; ++i)
        cin >> a[i];
    for (int i = 0; i < n + 1; ++i)
        map[i] = 0;
    int i, j;
    queue <QuJ> q;
    for (i = 0, j = 1, map[a[0]]++; i < n && j < n; ++j) {
        map[a[j]]++;
        if (map[a[j]] > 1) {
            for (int k = i; k < j; ++k) {
                map[a[k]]--;
                if (a[k] == a[j]) {
                    int tl = j - i;
                    if (tl > length) {
                        length = tl;
                        while (!q.empty()) {
                            q.pop();
                        }
                        QuJ temp;
                        temp.x = i + 1;
                        temp.y = j;
                        q.push(temp);
                        count = 1;
                    } else if (tl == length) {
                        QuJ temp;
                        temp.x = i + 1;
                        temp.y = j;
                        q.push(temp);
                        count++;
                    }
                    i = k + 1;
                    break;
                }
            }
        }
    }
    if (j - i > length) {
        length = j - i;
        while (!q.empty()) {
            q.pop();
        }
        QuJ temp;
        temp.x = i + 1;
        temp.y = j;
        q.push(temp);
        count = 1;
    } else if (j - i == length) {
        QuJ temp;
        temp.x = i + 1;
        temp.y = j;
        q.push(temp);
        count++;
    }
    cout << count << endl;
    while (!q.empty()) {
        QuJ temp = q.front();
        cout << temp.x << " " << temp.y << endl;
        q.pop();
    }
}
// 64 位输出请用 printf("%lld")