Create maximize-the-minimum-powered-city.py

Author: kamyu104

Python/maximize-the-minimum-powered-city.py

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+# Time:  O(nlogk)
+# Space: O(n)
+
+# binary search, sliding window, greedy
+class Solution(object):
+    def maxPower(self, stations, r, k):
+        """
+        :type stations: List[int]
+        :type r: int
+        :type k: int
+        :rtype: int
+        """
+        def min_power():
+            mn = float("inf")
+            curr = sum(stations[i] for i in xrange(r))
+            for i in xrange(len(stations)):
+                if i+r < len(stations):
+                    curr += stations[i+r]
+                if i >= r+1:
+                    curr -= stations[i-(r+1)]
+                mn = min(mn, curr)
+            return mn
+    
+        def check(target):
+            arr = stations[:]
+            curr = sum(arr[i] for i in xrange(r))
+            cnt = k
+            for i in xrange(len(arr)):
+                if i+r < len(arr):
+                    curr += arr[i+r]
+                if i >= r+1:
+                    curr -= arr[i-(r+1)]
+                if curr >= target:
+                    continue
+                d = target-curr
+                if d > cnt:
+                    return False
+                cnt -= d
+                curr += d
+                if i+r < len(arr):
+                    arr[i+r] += d
+            return True
+
+        mn = min_power() 
+        left, right = mn, mn+k
+        while left <= right:
+            mid = left + (right-left)//2
+            if not check(mid):
+                right = mid-1
+            else:
+                left = mid+1
+        return right
+