Create minimum-lines-to-represent-a-line-chart.py

Author: kamyu104

Python/minimum-lines-to-represent-a-line-chart.py

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+# Time:  O(nlogn)
+# Space: O(1)
+
+# sort, math, gcd
+class Solution(object):
+    def minimumLines(self, stockPrices):
+        """
+        :type stockPrices: List[List[int]]
+        :rtype: int
+        """
+        def gcd(a, b):
+            while b:
+                a, b = b, a%b
+            return a
+    
+        stockPrices.sort()
+        result = 0
+        prev = None
+        for i in xrange(1, len(stockPrices)):
+            dy, dx = stockPrices[i][1]-stockPrices[i-1][1], stockPrices[i][0]-stockPrices[i-1][0]
+            g = gcd(dy, dx)
+            if not prev or prev != (dy//g, dx//g):
+                prev = (dy//g, dx//g)
+                result += 1
+        return result