LEETCODE算法:56. Merge Intervals

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题目

Given a collection of intervals, merge all overlapping intervals.

Example 1:

Input: [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6]. Example 2:

Input: [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considered overlapping. NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

题解

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//排序合并
class Solution {
    static bool cmp(vector<int> &a,vector<int> &b)
    {
        if(a[0]!=b[0]) return a[0]<b[0];
        else return a[1]<b[1]; 
    }
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        vector<vector<int>> res;
        if(intervals.size()==0) return res;
        sort(intervals.begin(),intervals.end(),cmp);
        for(int i=0;i<intervals.size();i++)
        {
            if(i==0||intervals[i][0]>res.back()[1])
            {
                res.push_back(vector<int>{intervals[i][0],intervals[i][1]});
            }else{
                res.back()[1]=max(res.back()[1],intervals[i][1]);
            }
        }
        return res;
    }

};