Create execution-of-all-suffix-instructions-staying-in-a-grid.py

Author: kamyu104

Python/execution-of-all-suffix-instructions-staying-in-a-grid.py

@@ -0,0 +1,39 @@
+# Time:  O(m)
+# Space: O(m)
+
+import collections
+
+
+class Solution(object):
+    def executeInstructions(self, n, startPos, s):
+        """
+        :type n: int
+        :type startPos: List[int]
+        :type s: str
+        :rtype: List[int]
+        """
+        directions = {'U':(-1, 0), 'R':(0, 1), 'D':(1, 0), 'L':(0, -1)}
+        (x0, y0), (x, y) = startPos, (0, 0)
+        result = range(len(s), 0, -1)
+        lookup_x = collections.defaultdict(list)
+        lookup_y = collections.defaultdict(list)
+        lookup_x[x0-x].append(0)
+        lookup_y[y0-y].append(0)
+        for i, d in enumerate(s):
+            dx, dy = directions[d]
+            x, y = x+dx, y+dy
+            for k in n-x, -x-1:
+                if k not in lookup_x:
+                    continue
+                for j in lookup_x[k]:
+                    result[j] = min(result[j], i-j)
+                lookup_x[k] = []
+            for k in n-y, -y-1:
+                if k not in lookup_y:
+                    continue
+                for j in lookup_y[k]:
+                    result[j] = min(result[j], i-j)
+                lookup_y[k] = []
+            lookup_x[x0-x].append(i+1)
+            lookup_y[y0-y].append(i+1)
+        return result