Combinatorics

Author: deathlyhallows010

Math/Grid Unique Path.py

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+# https://www.interviewbitcom/problems/grid-unique-paths/
+
+# Grid Unique Path
+
+# Input : A = 2, B = 2
+# Output : 2
+# 2 possible routes : (0, 0) -> (0, 1) -> (1, 1) 
+# OR : (0, 0) -> (1, 0) -> (1, 1)
+
+
+class Solution:
+ # @param A : integer
+ # @param B : integer
+ # @return an integer
+ def uniquePaths(self,rows, cols):
+ 
+ if rows==1 or cols == 1:
+ return 1
+ 
+ a = [[1] + [0]*(cols-1)]*rows
+ a[0] = [1]*cols
+ 
+ for i in range(1,rows):
+ for j in range(1,cols):
+ a[i][j] = a[i-1][j] + a[i][j-1]
+
+ 
+ 
+ return a[rows-1][cols-1]