715. Range Module

Posted 2021-01-24 ruruozhenhao

A Range Module is a module that tracks ranges of numbers. Your task is to design and implement the following interfaces in an efficient manner.

 

• addRange(int left, int right) Adds the half-open interval [left, right), tracking every real number in that interval. Adding an interval that partially overlaps with currently tracked numbers should add any numbers in the interval [left, right) that are not already tracked.

 

 

• queryRange(int left, int right) Returns true if and only if every real number in the interval [left, right) is currently being tracked.

 

 

• removeRange(int left, int right) Stops tracking every real number currently being tracked in the interval [left, right).

 

Example 1:

addRange(10, 20): null
removeRange(14, 16): null
queryRange(10, 14): true (Every number in [10, 14) is being tracked)
queryRange(13, 15): false (Numbers like 14, 14.03, 14.17 in [13, 15) are not being tracked)
queryRange(16, 17): true (The number 16 in [16, 17) is still being tracked, despite the remove operation)

 

Note:

• A half open interval [left, right) denotes all real numbers left <= x < right.
• 0 < left < right < 10^9 in all calls to addRange, queryRange, removeRange.
• The total number of calls to addRange in a single test case is at most 1000.
• The total number of calls to queryRange in a single test case is at most 5000.
• The total number of calls to removeRange in a single test case is at most 1000.

 

 

Approach #1: C++. [Using Vector]

class RangeModule {
public:
    RangeModule() {
        
    }
    
    void addRange(int left, int right) {
        vector<pair<int, int>> new_ranges;
        bool inserted = false;
        
        for (const auto& it : ranges_) {
            if (it.first > right && !inserted) {
                new_ranges.emplace_back(left, right);
                inserted = true;
            }
            if (it.first > right || it.second < left) {
                new_ranges.push_back(it);
            } else {
                left = min(left, it.first);
                right = max(right, it.second);
            }
        }
        if (!inserted) new_ranges.emplace_back(left, right);
        ranges_.swap(new_ranges);
    }
    
    bool queryRange(int left, int right) {
        int l = 0;
        int r = ranges_.size() - 1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (ranges_[mid].first <= left && ranges_[mid].second >= right) 
                return true;
            else if (ranges_[mid].first > right) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        return false;
    }
    
    void removeRange(int left, int right) {
        vector<pair<int, int>> new_ranges;
        for (const auto& it : ranges_) {
            if (it.second <= left || it.first >= right) {
                new_ranges.emplace_back(it);
            } else {
                if (it.first < left) 
                    new_ranges.emplace_back(it.first, left);
                if (it.second > right)
                    new_ranges.emplace_back(right, it.second);
            }
        }
        ranges_.swap(new_ranges);
    }
    
private:
    vector<pair<int, int>> ranges_;
};

/**
 * Your RangeModule object will be instantiated and called as such:
 * RangeModule obj = new RangeModule();
 * obj.addRange(left,right);
 * bool param_2 = obj.queryRange(left,right);
 * obj.removeRange(left,right);
 */

　　

there are some notes about STL.

1. the difference between emplace_back and push_back.

2. emplace vs insert.

3. the method of swap in vector.

 

Approach #2: