Google Phone Interview Mock 1

Author: Partho Biswas

README.md

@@ -166,6 +166,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |55| **[683. K Empty Slots](https://tinyurl.com/rbyxknc)** | [Python](https://tinyurl.com/wu6rdaw/683_K_Empty_Slots.py), [Swift](https://tinyurl.com/wuja3c4/683_K_Empty_Slots.swift) | [Art 1](https://tinyurl.com/qsenvnd), [Art 2](https://tinyurl.com/u7g6hhy), [Art 3](https://tinyurl.com/vw42pp7) | Hard | TODO: Check monotonic queue approach. Solved it with sliding widow |
 |56| **[849. Maximize Distance to Closest Person](https://tinyurl.com/v44bs88)** | [Python](https://tinyurl.com/wu6rdaw/849_Maximize_Distance_to_Closest_Person.py), [Swift](https://tinyurl.com/wuja3c4/849_Maximize_Distance_to_Closest_Person.swift) | [Art 1](https://tinyurl.com/qsenvnd) | Easy | Not so easy and intuitive. Can be solve is a variety of way. I have used Binary search(A bit over engineered solution). Can be simplifies |
 |57| **[283. Move Zeroes](https://tinyurl.com/y5kxjuvc)** | [Python](https://tinyurl.com/wu6rdaw/283_Move_Zeroes.py), [Swift](https://tinyurl.com/wuja3c4/283_Move_Zeroes.swift) | --- | Easy | Not so easy and intuitive. Uses fast and slow pointer |
+|58| **[163. Missing Ranges](https://tinyurl.com/s297jm7)** | [Python](https://tinyurl.com/wu6rdaw/163_Missing_Ranges.py), [Swift](https://tinyurl.com/wuja3c4/163_Missing_Ranges.swift) | --- | Medium | Man, it's a very trick problem |
 
 
 </p>
@@ -212,6 +213,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |31| **[949. Largest Time for Given Digits](https://tinyurl.com/ux8dk9e)** | [Python](https://tinyurl.com/wu6rdaw/949_Largest_Time_for_Given_Digits.py), [Swift](https://tinyurl.com/wuja3c4/949_Largest_Time_for_Given_Digits.swift) | --- | Easy | Not so easy |
 |32| [788. Rotated Digits](https://tinyurl.com/t9gelfm) | [Python](https://tinyurl.com/wu6rdaw/788_Rotated_Digits.py), [Swift](https://tinyurl.com/wuja3c4/788_Rotated_Digits.swift) | --- | Easy | --- |
 |33| [388. Longest Absolute File Path](https://tinyurl.com/svfa3rc) | [Python](https://tinyurl.com/wu6rdaw/388_Longest_Absolute_File_Path.py), [Swift](https://tinyurl.com/wuja3c4/388_Longest_Absolute_File_Path.swift) | --- | Medium | --- |
+|34| [616. Add Bold Tag in String](https://tinyurl.com/taftav2) | [Python](https://tinyurl.com/wu6rdaw/616_Add_Bold_Tag_in_String.py), [Swift](https://tinyurl.com/wuja3c4/616_Add_Bold_Tag_in_String.swift) | --- | Medium | Merge intervals(hidden) |
 
 
 </p>

leetcode.com/python/163_Missing_Ranges.py

@@ -0,0 +1,21 @@
+class Solution(object):
+    def findMissingRanges(self, nums, lower, upper):
+        """
+        :type nums: List[int]
+        :type lower: int
+        :type upper: int
+        :rtype: List[str]
+        """
+        nums.insert(0, lower - 1)
+        nums.append(upper + 1)
+        res = []
+        i = 0
+        while i < len(nums) - 1:
+            leftRage, rightRange = nums[i], nums[i + 1]
+            if leftRage != (rightRange - 1):
+                if rightRange - leftRage == 2:
+                    res.append(str(rightRange - 1))
+                elif rightRange - leftRage > 2:
+                    res.append("{}->{}".format(leftRage + 1, rightRange - 1))
+            i += 1
+        return res

leetcode.com/python/346_Moving_Average_from_Data_Stream.py

@@ -1,27 +1,24 @@
 from collections import deque
 
-
 class MovingAverage(object):
 
-    def __init__(self, size: int):
+    def __init__(self, size):
         """
         Initialize your data structure here.
         :type size: int
         """
         self.size = size
-        self.queue = deque()
-        self.widowSum = 0
+        self.nums = deque()
 
-    def next(self, val: int) -> float:
+    def next(self, val):
         """
         :type val: int
         :rtype: float
         """
-        self.queue.append(val)
-        tail = self.queue.popleft() if len(self.queue) > self.size else 0
-        self.widowSum = self.widowSum - tail + val
-        res = self.widowSum / min(len(self.queue), self.size)
-        return res
+        if len(self.nums) >= self.size:
+            self.nums.popleft()
+        self.nums.append(val)
+        return float(float(sum(self.nums)) / float(len(self.nums)))
 
 # Your MovingAverage object will be instantiated and called as such:
 # obj = MovingAverage(size)

leetcode.com/python/616_Add_Bold_Tag_in_String.py

@@ -0,0 +1,51 @@
+# Approach 1: Merge intervals
+#   Step 1: create a list of tuples/intervals with opening/closing positions, e.g. (open_index, close_index)
+#   Step 2: merge the list of intervals (see https://leetcode.com/problems/merge-intervals/)
+#   Step 3: go through the merged interval list and insert the tags into the string
+class Solution(object):
+    def addBoldTag(self, s, dict):
+        """
+        :type s: str
+        :type dict: List[str]
+        :rtype: str
+        """
+        locations = []
+        # generate the word intervals
+        for word in dict:
+            startIdx = s.find(word)
+            while startIdx != -1:  # "s" can contain same word multiple times ad overlapped
+                locations.append([startIdx, startIdx + len(word) - 1])
+                startIdx = s.find(word, startIdx + 1)
+
+        if not locations:
+            return s
+
+        # merge the intervals
+        locations.sort(key=lambda x: x[0])
+        locationsMerged = []
+        startIdx, endIdx = locations[0][0], locations[0][1]
+        for i in range(1, len(locations)):
+            nextStart, nextEnd = locations[i][0], locations[i][1]
+            if nextStart <= endIdx + 1:  # since, if the strings are consequtive
+                endIdx = max(endIdx, nextEnd)
+            else:
+                locationsMerged.append([startIdx, endIdx])
+                startIdx, endIdx = nextStart, nextEnd
+        locationsMerged.append([startIdx, endIdx])
+
+        # gennerate the old tagged string
+        resultStr = ""
+        startIdx, endIdx = locationsMerged[0][0], locationsMerged[0][1]
+        resultStr += s[0:startIdx]
+        for i in range(len(locationsMerged)):
+            nextStart, nextEnd = locationsMerged[i][0], locationsMerged[i][1]
+            if endIdx < nextStart:
+                resultStr += s[endIdx + 1:nextStart]
+            strToBold = s[nextStart:nextEnd + 1]
+            if strToBold:
+                resultStr += "<b>{}</b>".format(strToBold)
+            else:
+                resultStr += s[endIdx + 1:nextStart]
+            startIdx, endIdx = nextStart, nextEnd
+        resultStr += s[endIdx + 1:]
+        return resultStr