2020-07-27

Author: JiayangWu

.DS_Store

@@ -10,4 +10,5 @@ def isSubsequence(self, s, t):
             if s[i] == t[j]:
                 i += 1
             j += 1
-        return i == len(s)
+        # test
+        return i == len(s) 

0392.判断子序列/0392-判断子序列.py

@@ -0,0 +1,10 @@
+class Solution(object):
+    def countOdds(self, low, high):
+        """
+        :type low: int
+        :type high: int
+        :rtype: int
+        """
+        if low % 2 + high % 2 == 0:
+                return (high - low) // 2
+        return 1 + (high - low) // 2

1523.在区间范围内统计奇数数目/1523-在区间范围内统计奇数数目.py

@@ -0,0 +1,25 @@
+class Solution(object):
+    def numOfSubarrays(self, arr):
+        """
+        :type arr: List[int]
+        :rtype: int
+        """
+        prefix_sum = [0 for _ in arr]
+        prefix_sum[0] = arr[0]
+
+        for i in range(1, len(arr)):
+            prefix_sum[i] = prefix_sum[i - 1] + arr[i]
+
+        MOD = 10 ** 9 + 7
+        even, odd = 1, 0
+        res = 0
+        for i in range(len(arr)):
+            if prefix_sum[i] % 2 == 0:
+                res += odd 
+                even += 1
+            else:
+                res += even
+                odd += 1
+            res = res % MOD 
+        return res 
+            

1524.和为奇数的子数组数目/1524-和为奇数的子数组数目.py

@@ -0,0 +1,25 @@
+class Solution(object):
+    def numSplits(self, s):
+        """
+        :type s: str
+        :rtype: int
+        """
+        from collections import defaultdict
+        import copy
+        rs = defaultdict(set)
+
+        for i in range(len(s) - 1, -1, -1):
+            if i == len(s) - 1:
+                rs[i] = set(s[i])
+            else:
+                rs[i] = copy.deepcopy(rs[i + 1])
+                rs[i].add(s[i])
+                
+        ls = set(s[0])
+        res = 0
+        for i in range(len(s) - 1):
+            ls.add(s[i])
+            if len(ls) == len(rs[i + 1]):
+                res += 1
+      
+        return res