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Author: Chris Wu

problems/egions-cut-by-slashes.py

@@ -0,0 +1,44 @@
+class Solution(object):
+    def regionsBySlashes(self, grid):
+        region = 1
+        dsu = DSU()
+        N = len(grid)
+        
+        #Union the border lines
+        for i in xrange(N):
+            dsu.union((i, 0), (i+1, 0))
+            dsu.union((i, N), (i+1, N))
+        for j in xrange(N):
+            dsu.union((0, j), (0, j+1))
+            dsu.union((N, j), (N, j+1))
+
+        #Iterate through slashes and connect the dots
+        #If the slash connects two already connected dots, the region will increament by one
+        for i, row in enumerate(grid):
+            for j, slash in enumerate(row):
+                if slash=='/':
+                    if not dsu.union((j+1, i), (j, i+1)):
+                        region += 1
+                elif slash=='\\':
+                    if not dsu.union((j, i), (j+1, i+1)):
+                        region += 1
+        return region
+
+class DSU(object):
+    def __init__(self):
+        self.parant = {}
+    
+    def find(self, x):
+        if x not in self.parant:
+            self.parant[x] = x
+
+        if self.parant[x]!=x:
+            self.parant[x] = self.find(self.parant[x])
+
+        return self.parant[x]
+
+    def union(self, x, y):
+        xr, yr = self.find(x), self.find(y)
+        if xr==yr: return False
+        self.parant[yr] = xr
+        return True