Create maximum-number-of-removable-characters.py

Author: kamyu104

Python/maximum-number-of-removable-characters.py

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+# Time:  O(rlogn)
+# Space: O(r)
+
+# if r = O(1), this is better
+class Solution(object):
+    def maximumRemovals(self, s, p, removable):
+        """
+        :type s: str
+        :type p: str
+        :type removable: List[int]
+        :rtype: int
+        """
+        def check(s, p, removable, x):
+            lookup = set(removable[i] for i in xrange(x))
+            j = 0
+            for i in xrange(len(s)):
+                if i in lookup or s[i] != p[j]:
+                    continue
+                j += 1
+                if j == len(p):
+                    return True
+            return False
+
+        left, right = 0, len(removable)
+        while left <= right:
+            mid = left + (right-left)//2
+            if not check(s, p, removable, mid):
+                right = mid-1
+            else:
+                left = mid+1
+        return right
+
+
+# Time:  O(rlogn)
+# Space: O(n)
+# if r = O(n), this is better
+class Solution2(object):
+    def maximumRemovals(self, s, p, removable):
+        """
+        :type s: str
+        :type p: str
+        :type removable: List[int]
+        :rtype: int
+        """
+        def check(s, p, lookup, x):
+            j = 0
+            for i in xrange(len(s)):
+                if lookup[i] <= x or s[i] != p[j]:
+                    continue
+                j += 1
+                if j == len(p):
+                    return True
+            return False
+
+        lookup = [float("inf")]*len(s)
+        for i, r in enumerate(removable):
+            lookup[r] = i+1
+        left, right = 0, len(removable)
+        while left <= right:
+            mid = left + (right-left)//2
+            if not check(s, p, lookup, mid):
+                right = mid-1
+            else:
+                left = mid+1
+        return right