2019-08-30

Author: Jiayang Wu

0270.最接近的二叉搜索树值/0270-最接近的二叉搜索树值.py

@@ -0,0 +1,29 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def closestValue(self, root, target):
+        """
+        :type root: TreeNode
+        :type target: float
+        :rtype: int
+        """
+        
+        def inOrder(node):
+            if not node:
+                return []
+            return inOrder(node.left) + [node.val] + inOrder(node.right)
+        
+        l = inOrder(root) 
+        res = 0
+        min_sub = float("inf")
+        
+        for num in l:
+            if abs(num - target) < min_sub:
+                min_sub = abs(num - target)
+                res = num
+        return res

0271.字符串的编码与解码/0271-字符串的编码与解码.py

@@ -0,0 +1,21 @@
+class Codec:
+
+    def encode(self, strs):
+        """Encodes a list of strings to a single string.
+        
+        :type strs: List[str]
+        :rtype: str
+        """
+        return strs
+
+    def decode(self, s):
+        """Decodes a single string to a list of strings.
+        
+        :type s: str
+        :rtype: List[str]
+        """
+        return s
+
+# Your Codec object will be instantiated and called as such:
+# codec = Codec()
+# codec.decode(codec.encode(strs))

0272.最接近的二叉搜索树值II/0272-最接近的二叉搜索树值II.py

@@ -0,0 +1,34 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+from heapq import *
+class Solution(object):
+    def closestKValues(self, root, target, k):
+        """
+        :type root: TreeNode
+        :type target: float
+        :type k: int
+        :rtype: List[int]
+        """
+        def inOrder(node):
+            if not node:
+                return []
+            return inOrder(node.left) + [node.val] + inOrder(node.right)
+        
+        l = inOrder(root)
+        subs = []
+        heapify(subs)
+        for num in l:
+            sub = abs(target - num)
+            heappush(subs, (-sub, num))
+            if len(subs) > k:
+                heappop(subs)
+                
+        res = []
+        for sub, num in subs:
+            res.append(num)
+        return res
+            

0274.H指数/0274-H指数.py

@@ -4,17 +4,22 @@ def hIndex(self, citations):
         :type citations: List[int]
         :rtype: int
         """
+        # 0 1 3 6 5
         citations.sort()
-        l = len(citations)
-        lo, hi = 0, l - 1
+        n = len(citations)
+        left, right = 0, len(citations) - 1
         res = 0
-        while(lo <= hi):
-            mid = lo + (hi - lo) // 2
-            cnt = l - mid #包括mid自身右边还有的元素个数
-            if citations[mid] >= cnt: 
+        while left <= right:
+            
+            mid = (left + right) // 2
+            
+            cnt = n - mid
+            # print left, right, mid, citations[mid], cnt, citations
+            if citations[mid] < cnt:
+                left = mid + 1
+            elif citations[mid] >= cnt:
                 res = cnt
-                hi = mid -1
-            else:
-                lo = mid + 1
+                right = mid - 1
         return res
-        
+            
+            

0275.H指数II/0275-H指数II.py

@@ -4,16 +4,18 @@ def hIndex(self, citations):
         :type citations: List[int]
         :rtype: int
         """
-        l = len(citations)
-        lo, hi = 0, l - 1
+        n = len(citations)
+        left, right = 0, len(citations) - 1
         res = 0
-        while(lo <= hi):
-            mid = lo + (hi - lo) // 2
-            cnt = l - mid #包括mid自身右边还有的元素个数
-            if citations[mid] >= cnt: 
+        while left <= right:
+            
+            mid = (left + right) // 2
+            
+            cnt = n - mid
+            # print left, right, mid, citations[mid], cnt, citations
+            if citations[mid] < cnt:
+                left = mid + 1
+            elif citations[mid] >= cnt:
                 res = cnt
-                hi = mid -1
-            else:
-                lo = mid + 1
-        return res
-                
+                right = mid - 1
+        return res