Solve 69. Sqrt(x)

python/69_sqrtx.py

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+class Solution:
+    def mySqrt(self, x: int) -> int:
+        # Use Newton-Raphson iteration
+        # y**2 - x = 0 = f(y)
+        # f'(y) = 2y
+        # y = y - (y**2 - x)/(2y)
+        y = 1
+        close_enough = False
+        while not close_enough:
+            y -= (y*y-x)/(2*y)
+            close_enough = y*y - x <= 0.1 and (y+1)*(y+1) > x
+        return floor(y)