作业

YujueY · YujueY · commit 776e0d57dad7 · 2020-08-08T21:32:31.000+08:00
diff --git a/Week09/125.py b/Week09/125.py
@@ -0,0 +1,4 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        res = "".join(ch.lower() for ch in s if ch.isalnum())
+        return res == res[::-1]
diff --git a/Week09/14.py b/Week09/14.py
@@ -0,0 +1,40 @@
+class Solution1:
+    def longestCommonPrefix(self, strs: List[str]) -> str:
+        if not strs:
+            return ""
+        s = len(strs)
+        if s == 1:
+            return strs[0]
+        n = len(min(strs))
+        string = ""
+        flag = True
+        for j in range(n):
+            if flag:
+                for l in range(1, s):
+                    if strs[l][j] == strs[l-1][j]:
+                        if l == s-1:
+                            string += strs[l][j]
+                    else:
+                        flag = False
+                        break
+        return string
+
+class Solution2:
+    def longestCommonPrefix(self, strs: List[str]) -> str:
+        s = ""
+        for i in zip(*strs):
+            if len(set(i)) == 1:
+                s += i[0]
+            else:
+                break           
+        return s    
+
+class Solution3:
+    def longestCommonPrefix(self, strs: List[str]) -> str:
+        if not strs: return ""
+        str0 = min(strs)
+        str1 = max(strs)
+        for i in range(len(str0)):
+            if str0[i] != str1[i]:
+                return str0[:i]
+        return str0
diff --git a/Week09/344.py b/Week09/344.py
@@ -0,0 +1,17 @@
+class Solution1:
+    def reverseString(self, s: List[str]) -> None:
+        """
+        Do not return anything, modify s in-place instead.
+        """
+        n = len(s)
+        mid = n // 2
+        for i in range(mid):
+            s[i], s[n-i-1] = s[n-i-1], s[i]
+        return s
+        
+class Solution1:
+    def reverseString(self, s: List[str]) -> None:
+        """
+        Do not return anything, modify s in-place instead.
+        """
+        return s.reverse()
diff --git a/Week09/541.py b/Week09/541.py
@@ -0,0 +1,9 @@
+class Solution:
+    def reverseStr(self, s: str, k: int) -> str:
+        if not s:
+            return s
+        a = list(s)
+        n = len(s)
+        for i in range(0, n, 2*k):
+            a[i:i+k] = reversed(a[i:i+k])
+        return "".join(a)
diff --git a/Week09/58.py b/Week09/58.py
@@ -0,0 +1,21 @@
+class Solution1:
+    def lengthOfLastWord(self, s: str) -> int:
+        string = s.split()
+        return len(string[-1]) if string else 0
+
+class Solution2:
+    def lengthOfLastWord(self, s: str) -> int:
+        if not s and len(s) == 0:
+            return 0
+        count = 0
+        for i in s[::-1]:
+            if i == " ":
+                if count == 0:
+                    continue
+                else:
+                    break
+            else:
+                count += 1
+            
+        return count
+
diff --git a/Week09/680.py b/Week09/680.py
@@ -0,0 +1,19 @@
+class Solution:
+    def validPalindrome(self, s: str) -> bool:
+        def check(low, high):
+            i, j = low, high
+            while i < j:
+                if s[i] != s[j]:
+                    return False
+                i += 1
+                j -= 1
+            return True
+        
+        low, high = 0, len(s)-1
+        while low < high:
+            if s[low] == s[high]:
+                low += 1
+                high -= 1
+            else:
+                return check(low+1, high) or check(low, high-1)
+        return True
diff --git a/Week09/709.py b/Week09/709.py
@@ -0,0 +1,14 @@
+class Solution1:
+    def toLowerCase(self, str: str) -> str:
+        dic = {'A':'a', 'B':'b', 'C':'c', 'D':'d', 'E':'e', 'F':'f',
+               'G':'g', 'H':'h', 'I':'i', 'J':'j', 'K':'k', 'L':'l',
+               'M':'m', 'N':'n', 'O':'o','P':'p', 'Q':'q', 'R':'r',
+               'S':'s', 'T':'t', 'U':'u', 'V':'v', 'W':'w', 'X':'x',
+               'Y':'y', 'Z':'z'}
+
+        return "".join([dic.get(s, s) for s in str])
+
+
+class Solution2:
+    def toLowerCase(self, str: str) -> str:
+    return str.lower()
diff --git a/Week09/746.py b/Week09/746.py
@@ -0,0 +1,5 @@
+class Solution:
+    def minCostClimbingStairs(self, cost: List[int]) -> int:
+        for i in range(2, len(cost)):
+            cost[i] = min(cost[i-1], cost[i-2]) + cost[i]
+        return min(cost[-1], cost[-2])
