题解 | #合并区间#

/**
 * struct Interval {
 *	int start;
 *	int end;
 *	Interval(int s, int e) : start(start), end(e) {}
 * };
 */
#include <iterator>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param intervals Interval类vector 
     * @return Interval类vector
     */
    void QuickSort(vector<Interval> &arr,int l,int r)
    {
        if(!arr.empty())
        {
            int mid = Split(arr,l,r);
            QuickSort(arr, l, mid-1);
            QuickSort(arr, mid+1, r);
        }
    }

    int Split(vector<Interval> &arr,int l,int r)
    {
        Interval pivot = arr[l];
        while(l < r)
        {
            while(arr[r].start > pivot.start && l<r)
            {
                r--;
            }
            if(l < r)
            {
                swap(arr[l++],arr[r]);
            }
            while(arr[l].start < pivot.start && l<r)
            {
                l++;
            }
            if(l < r)
            {
                swap(arr[l],arr[r--]);
            }
        }
        return l;
    }

    static bool cmp(Interval& a,Interval& b)
    {
        return a.start < b.start;
    }

    vector<Interval> merge(vector<Interval>& intervals) {
        // write code here
        if(intervals.size() == 0) return intervals;
        //QuickSort(intervals,0,intervals.size()-1);
        sort(intervals.begin(),intervals.end(),cmp);
        vector<Interval> ans;
        ans.push_back(intervals.front());
        for(int i = 1;i<intervals.size();i++)
        {
            if(intervals[i].start <= ans.back().end)
            {
                ans.back().end = max(intervals[i].end,ans.back().end);
            }
            else 
            {
                ans.push_back(intervals[i]);
            }
        }
        return ans;
    }
};