add leetcode 56,57 about sort problem

code@xukaixuan/demo56 merge-intervals/56.merge-intervals.py

@@ -0,0 +1,18 @@
+#
+# @lc app=leetcode id=56 lang=python3
+#
+# [56] Merge Intervals
+#
+class Solution:
+    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
+        ans = []
+        for invt in sorted(intervals,key = lambda x :x[0]):
+            if (ans and ans[-1][-1] >= invt[0]):
+                ans[-1][-1] = max(invt[-1],ans[-1][-1])
+            else:
+                ans.append(invt)
+        return ans
+
+
+
+

code@xukaixuan/demo56 merge-intervals/readme.md

@@ -0,0 +1,18 @@
+## 56 Merge Intervals
+### 题目描述
+Given a collection of intervals, merge all overlapping intervals.
+```
+# example1
+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].
+```
+
+```
+Input: [[1,4],[4,5]]
+Output: [[1,5]]
+Explanation: Intervals [1,4] and [4,5] are considered overlapping.
+```
+### 考察知识点
+
+排序 数组

code@xukaixuan/demo57 insert-intervals/57.insert-interval.py

@@ -0,0 +1,16 @@
+#
+# @lc app=leetcode id=57 lang=python3
+#
+# [57] Insert Interval
+#
+class Solution:
+    def insert(self, intervals: List[List[int]], newInterval: List[int]) -> List[List[int]]:
+        s,e = newInterval[0],newInterval[-1]
+        left = [i for i in intervals if i[-1]<s]
+        right = [i for i in intervals if i[0]>e]
+        if left + right != intervals:
+            s = min(s,intervals[len(left)][0])
+            e = max(e,intervals[~len(right)][-1])
+        return left + [Interval(s,e)] +right
+
+

code@xukaixuan/demo57 insert-intervals/readme.md

@@ -0,0 +1,19 @@
+## Insert Interval
+### 考察知识点
+排序 
+### description
+Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).
+
+You may assume that the intervals were initially sorted according to their start times.
+
+Example 1:
+```
+Input: intervals = [[1,3],[6,9]], newInterval = [2,5]
+Output: [[1,5],[6,9]]
+```
+Example 2:
+```
+Input: intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
+Output: [[1,2],[3,10],[12,16]]
+Explanation: Because the new interval [4,8] overlaps with [3,5],[6,7],[8,10].
+```