LeetCode 1893. Check if All the Integers in a Range Are Covered

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class Solution {
public:
    bool isCovered(vector<vector<int>>& ranges, int l, int r) {
        for (int i = l; i <= r; ++i) {
            bool ans = false;
            for (const auto& x : ranges)
                if (x[0] <= i && i <= x[1]) {
                    ans = true;
                    break;
                }
            if (!ans)
                return ans;
        }
        return true;
    }
};
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class Solution {
public:
    bool isCovered(vector<vector<int>>& ranges, int left, int right) {
        int n = ranges.size(), s = 0;
        int diff[52] = {0};
        for (auto &r : ranges) ++diff[r[0]], --diff[r[1] + 1];
        for (int i = 1; i < left; ++i) s += diff[i];
        for (int i = left; i <= right; ++i)
            if ((s += diff[i]) == 0)
                return false;
        return true;
    }
};