Binary-Search-Brilliance/Boundaries.cpp at master · Grecil/Binary-Search-Brilliance · GitHub

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#include <bits/stdc++.h>
using namespace std;

int lower_bound(const vector<int>& arr, int target) {
    int left = 0, right = arr.size();

    while (left < right) {
        int mid = left + (right - left) / 2;
        if (arr[mid] < target) {
            left = mid + 1;
        } else {
            right = mid;
        }
    }

    return left;
}

int upper_bound(const vector<int>& arr, int target) {
    int left = 0, right = arr.size();

    while (left < right) {
        int mid = left + (right - left) / 2;
        if (arr[mid] <= target) {
            left = mid + 1;
        } else {
            right = mid;
        }
    }

    return left;
}

int main() {
    int n, target;
    cin >> n >> target;

    vector<int> arr(n);
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
    }

    int lb = lower_bound(arr, target);
    int ub = upper_bound(arr, target);

    cout << lb << " " << ub << endl;

    return 0;
}