added leetcode question

14. Questions/leetcode 1011 - capacity to ship packages.py

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+# capacity to ship packages within D days | leetcode 1011 | https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/
+# binary search on a range of min and max capacity required 
+# min capacity = max(weights) and max capacity = sum(weights)
+
+class Solution:
+    def shipWithinDays(self, weights: list[int], days: int) -> int:
+        low, high = max(weights), sum(weights)
+        res = high
+
+        # check if days required for a capacity is less than D
+        def isPossible (capacity):
+            daysReq = 1
+            window = capacity
+            for weight in weights:
+                if window - weight < 0:
+                    window = capacity
+                    daysReq += 1
+                window -= weight
+
+            return daysReq <= days
+
+        # binary search on [min...max]
+        while low <= high:
+            mid = (high + low) // 2
+
+            if isPossible(mid):
+                res = min(res, mid)
+                high = mid - 1
+            else:
+                low = mid + 1
+
+        return res
+

14. Questions/leetcode 502 - ipo.py

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+# IPO | leetcode 502 | https://leetcode.com/problems/ipo/
+# min-heap to track capital and max-heap to track profits
+
+import heapq
+
+class Solution:
+    def findMaximizedCapital(self, k: int, w: int, profits: list[int], capital: list[int]) -> int:
+        maxHeap = []
+        minHeap = [(c, p) for c, p in zip(capital, profits)]
+        heapq.heapify(minHeap)
+
+        for _ in range(k):
+            while minHeap and minHeap[0][0] <= w:
+                _, p = heapq.heappop(minHeap)
+                heapq.heappush(maxHeap, -1 * p)
+            if not maxHeap:
+                break
+            w += -1 * heapq.heappop(maxHeap)
+
+        return w
+

14. Questions/leetcode 540 - single element in a sorted array.py

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+# single element in a sorted array | leetcode 540 | https://leetcode.com/problems/single-element-in-a-sorted-array/
+# binary search over sorted array; check if mid is even and mid is the first of the duplicates
+
+class Solution:
+    def singleNonDuplicate(self, nums: list[int]) -> int:
+        N = len(nums)
+        if N < 2:
+            return nums[0]
+        low, high, mid = 0, N, 0
+        while low <= high:
+            mid = low + ((high - low) // 2)
+
+            if mid == N - 1:
+                return nums[mid]
+
+            if nums[mid] == nums[mid - 1] or nums[mid] == nums[mid + 1]:
+                if (mid % 2 == 0) == (nums[mid] == nums[mid + 1]):
+                    low = mid
+                else:
+                    high = mid
+            else:
+                return nums[mid]
+
+        return nums[mid]

14. Questions/leetcode 989 - add to array form of integer.py

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+# add to array form of integer | leetcode 989 | https://leetcode.com/problems/add-to-array-form-of-integer
+
+class Solution:
+    def addToArrayForm(self, num: list[int], k: int) -> list[int]:
+        n = len(num) - 1
+        carry = 0
+        while k or carry:
+            k, digit = k // 10, k % 10
+            each = carry + digit
+            if n < 0:
+                num.insert(0, each % 10)
+            else:
+                each = each + num[n]
+                num[n] = each % 10
+            carry = each // 10
+            n -= 1
+
+        return num
+