从头做leetcode之leetcode 56 合并区间-优快云博客

本文链接：https://blog.youkuaiyun.com/cncxycpp/article/details/106349155

56.合并区间

给出一个区间的集合，请合并所有重叠的区间。

快速排序
先用快速排序排序，使得每个区间的左区间按顺序排列，再进行合并。

class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        if(intervals.size() < 2) return intervals;
        vector<vector<int> > res;
        Quicksort(intervals,0,intervals.size()-1);
        res.push_back(intervals[0]);
        int flag = 0;
        for(int i = 1;i < intervals.size();i++){
            if(res[flag][1] >= intervals[i][0] && res[flag][1] >= intervals[i][1]){
                continue;
            }
            else if(res[flag][1] >= intervals[i][0] && res[flag][1] < intervals[i][1]){
                res[flag][1]=intervals[i][1];
            }
            else{
                res.push_back(intervals[i]);
                flag++;
            }
        }
        return res;
    }
    void Quicksort(vector<vector<int>>& intervals,int left,int right){
        int start = left;
        int end = right;
        if(start >= end) return;
        vector<int> tmp(intervals[start]);
        while(start < end){
            while(start < end && intervals[end][0] > tmp[0]){
                end--;
            }
            if(start < end){
                intervals[start][0] = intervals[end][0];
                intervals[start][1] = intervals[end][1];
                start++;
            }
            while(start < end && intervals[start][0] < tmp[0]){
                start++;
            }
            if(start < end){
                intervals[end][0] = intervals[start][0];
                intervals[end][1] = intervals[start][1];
                end--;
            }
        }
        intervals[start][0] = tmp[0];
        intervals[start][1] = tmp[1];
        Quicksort(intervals,left,end-1);
        Quicksort(intervals,start+1,right);
    }
};