Leetcode insert interval

intervals.md

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+# Intervals
+
++ [Non-overlapping Intervals](#non-overlapping-intervals)
++ [Merge Intervals](#merge-intervals)
++ [Insert Interval](#insert-interval)
+
+
+
+## Non-overlapping intervals
+
+https://leetcode.com/problems/non-overlapping-intervals
+
+```python
+class Solution(object):
+    def eraseOverlapIntervals(self, intervals):
+        """
+        :type intervals: List[List[int]]
+        :rtype: int
+        """
+
+        intervals_count = len(intervals)
+        if intervals_count  <= 1:
+            return 0
+        rightsorted_intervals = sorted(intervals, key=lambda x: x[1])
+        counter = 0
+        last_end = float("-inf")
+        for interval in rightsorted_intervals:
+            if interval[0] >= last_end:
+                last_end = interval[1]
+                counter += 1
+        return intervals_count - counter
+
+```
+
+## Merge intervals
+
+https://leetcode.com/problems/merge-intervals/
+
+```python
+class Solution(object):
+    def merge(self, intervals):
+        """
+        :type intervals: List[List[int]]
+        :rtype: List[List[int]]
+        """
+
+        merged_intervals = []
+        for interval in sorted(intervals, key=lambda x: x[0]):
+            if merged_intervals and interval[0] <= merged_intervals[-1][1]:
+                merged_intervals[-1][1] = max(interval[1], merged_intervals[-1][1])
+            else:
+                merged_intervals += [interval]
+        return merged_intervals
+
+```
+
+## Insert interval
+
+https://leetcode.com/problems/insert-interval/
+
+```python
+class Solution(object):
+    def insert(self, intervals, newInterval):
+        """
+        :type intervals: List[List[int]]
+        :type newInterval: List[int]
+        :rtype: List[List[int]]
+        """
+
+        intervals.append(newInterval)
+        merged_intervals = []
+        for interval in sorted(intervals, key=lambda x: x[0]):
+            if merged_intervals and interval[0] <= merged_intervals[-1][1]:
+                merged_intervals[-1][1] = max(interval[1], merged_intervals[-1][1])
+            else:
+                merged_intervals += [interval]
+        return merged_intervals
+
+```