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Employee Free Time

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Description

https://leetcode.com/problems/employee-free-time/description/

Solution

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/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
class Solution {
    
public:
    bool static compare(Interval& a, Interval& b) {
        return a.start < b.start;
    }
    vector<Interval> employeeFreeTime(vector<vector<Interval>>& schedule) {
        vector<Interval> whole;
        for (auto& item : schedule) {
            for (auto& item2 : item) {
                whole.push_back(item2);
            }
        }
        sort(whole.begin(), whole.end(), compare);
        
        int pre = -1;
        vector<Interval> merged;
        for (int index = 0; index < whole.size(); ++index) {
            if (whole[index].start > pre) {
                merged.push_back(whole[index]);
            }else {
                merged[merged.size() - 1].end = 
                    max(whole[index].end, merged[merged.size() - 1].end);
            }
            pre = merged[merged.size() - 1].end;
        }
        vector<Interval> ret;
        for (int index = 0; index < merged.size() - 1; ++index) {
            ret.push_back(Interval(merged[index].end, merged[index + 1].start));
        }
        return ret;
    }
};