Non-overlapping Intervals | Leetcode 435 solution

435 . Non-overlapping Intervals 

Given an array of intervals intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.

 

Example 1:

Input: intervals = [[1,2],[2,3],[3,4],[1,3]]
Output: 1
Explanation: [1,3] can be removed and the rest of the intervals are non-overlapping.

Example 2:

Input: intervals = [[1,2],[1,2],[1,2]]
Output: 2
Explanation: You need to remove two [1,2] to make the rest of the intervals non-overlapping.

Example 3:

Input: intervals = [[1,2],[2,3]]
Output: 0
Explanation: You don't need to remove any of the intervals since they're already non-overlapping.

 

Constraints:

• 1 <= intervals.length <= 105
• intervals[i].length == 2
• -5 * 104 <= starti < endi <= 5 * 104

solution : 

class Solution { public:     int eraseOverlapIntervals(vector<vector<int>>& intervals) {       int size =  intervals.size();       sort(intervals.begin(), intervals.end());       if(size == 1)       {         return 0;       }       int count =0;       int previous = 0;       for(int  current = 1 ; current < size ; current++)       {         if(intervals[previous][1] > intervals[current][0] )         {           count++;           if(intervals[current][1] > intervals[previous][1])           {               // current += 1;               continue;           }           else           {                 // previous += 1;           }         }         previous = current ;       }         return count;     } };