2021-02-21

Author: JiayangWu

1539.第k个缺失的正整数/1539-第k个缺失的正整数.py

@@ -5,10 +5,11 @@ def findKthPositive(self, arr, k):
         :type k: int
         :rtype: int
         """
-        cnt = 0
-        s = set(arr)
-        for i in range(1, max(arr) + k + 1):
-            if i not in s:
-                cnt += 1
-            if cnt == k:
-                return i
+        arr = set(arr)
+        num = 1
+        while k:
+            if num not in arr:
+                k -= 1
+
+            num += 1
+        return num - 1

1540.K次操作转变字符串/1540-K次操作转变字符串.py

@@ -0,0 +1,36 @@
+class Solution(object):
+    def canConvertString(self, s, t, k):
+        """
+        :type s: str
+        :type t: str
+        :type k: int
+        :rtype: bool
+        """
+        from collections import defaultdict
+
+        if not s or not t or len(s) != len(t):
+            return False
+
+        d = list()
+
+        for i in range(len(s)):
+            if s[i] < t[i]:
+                d.append(ord(t[i]) - ord(s[i]))
+            elif s[i] > t[i]:
+                d.append(26 - ord(s[i]) + ord(t[i]))
+
+        d.sort()
+        res = 0
+        pre = None
+        for distance in d:
+            if not pre or pre != distance:
+                res = max(res, distance)
+                pre = distance
+                pre_cnt = 1
+            else:
+                res = max(res, 26 * pre_cnt + distance)
+                pre_cnt += 1
+            if res > k:
+                return False
+        return True
+

1541.平衡括号字符串的最少插入次数/1541-平衡括号字符串的最少插入次数.py

@@ -0,0 +1,39 @@
+class Solution(object):
+    def minInsertions(self, s):
+        """
+        :type s: str
+        :rtype: int
+        """
+        left_cnt, cons_right_cnt = 0, 0
+        res = 0
+        for ch in s:
+            if ch == "(":
+                if cons_right_cnt:
+                    if cons_right_cnt % 2: # add 1 to make it even
+                        res += 1
+                        cons_right_cnt += 1
+                    pair = min(left_cnt, cons_right_cnt // 2) # build all possible pairs
+                    left_cnt -= pair
+                    cons_right_cnt -= pair * 2
+
+                    if cons_right_cnt: # if two or more ) left
+                        res += cons_right_cnt // 2 # add "(" every 2 )
+                        cons_right_cnt = 0
+                left_cnt += 1
+            else:
+                cons_right_cnt += 1
+
+        if cons_right_cnt:
+            if cons_right_cnt % 2: # add 1 to make it even
+                res += 1
+                cons_right_cnt += 1
+            pair = min(left_cnt, cons_right_cnt // 2) # build all possible pairs
+            left_cnt -= pair
+            cons_right_cnt -= pair * 2
+
+            if cons_right_cnt: # if two or more ) left
+                res += cons_right_cnt // 2 # add "(" every 2 )
+                cons_right_cnt = 0
+
+        res += left_cnt * 2 # add 2 ) every (
+        return res