56. 合并区间

要求：rt
思路：

class Solution {
public:
    bool static cmp(vector<int> &a,vector<int> &b){
        return a[0]==b[0]?a[1]<b[1]:a[0]<b[0];
    }
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        vector<vector<int>> v;
        int n=intervals.size();
        sort(intervals.begin(),intervals.end(),cmp);
        v.push_back(intervals[0]);
        for(int i=1;i<n;++i){
            if(v.back()[1]<intervals[i][0])
                v.push_back(intervals[i]);
            else if(v.back()[1]<intervals[i][1])v.back()[1]=intervals[i][1];
        }
        return v;
    }
};