3468. Find the Number of Copy Arrays

You are given an array original of length n and a 2D array bounds of length n x 2, where bounds[i] = [ui, vi].

You need to find the number of possible arrays copy of length n such that:

1. (copy[i] - copy[i - 1]) == (original[i] - original[i - 1]) for 1 <= i <= n - 1.
2. ui <= copy[i] <= vi for 0 <= i <= n - 1.

Return the number of such arrays.

class Solution {
public:
    int countArrays(vector<int>& original, vector<vector<int>>& bounds) {
        long long l = bounds[0][0], r = bounds[0][1], n = original.size();
        for(int i = 1; i < n and l <= r; i++) {
            long long d = original[i] - original[i-1];
            l += d, r += d;
            long long le = bounds[i][0], ri = bounds[i][1];
            l = max(l, le);
            r = min(r, ri);
        }
        return max(0ll, r - l + 1);
    }
};