No.211 - LeetCode[56] Merge Intervals - 区间合并 - 经典

区间合并问题经常用排序来解决。

贪心O(NlogN)

/*
 * @lc app=leetcode id=56 lang=cpp
 *
 * [56] Merge Intervals
 */

// @lc code=start
class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        int N = intervals.size();
        vector<vector<int>> ans;
        if(N <= 0) return ans;
        sort(intervals.begin(),intervals.end(),[](vector<int>& a,vector<int>& b){return a[0]<b[0];});
        ans.push_back(vector<int>{intervals[0][0],intervals[0][1]});
        for(int i=1;i<N;i++){
            if(ans.back()[1] < intervals[i][0]) 
                ans.push_back(intervals[i]);
            else
                ans.back()[1] = max(ans.back()[1], intervals[i][1]);
        }
        return ans;
    }
};
// @lc code=end