added 1559_Detect_Cycles_In_2D_Grid.py

LeetCode/1559_Detect_Cycles_In_2D_Grid.py

@@ -0,0 +1,55 @@
+class Solution:
+    def __init__(self):
+        self.directionX = [-1,0,1,0]
+        self.directionY = [0,1,0,-1]
+    def isValid(self, x, y, N, M):
+        if x < N and x >= 0 and y < M and y >= 0:
+            return True
+        return False
+
+    def isCycle(self, x, y, arr, visited, parentX, parentY):
+        # Mark the current vertex as visited
+        visited[x][y] = True
+        N, M = len(arr), len(arr[0])
+
+        for k in range(4):
+            newX = x + self.directionX[k]
+            newY = y + self.directionY[k]
+            if self.isValid(newX, newY, N, M) and arr[newX][newY] == arr[x][y] and not (parentX == newX and parentY == newY):
+                if visited[newX][newY]:
+                    return True
+                else:
+
+                    check = self.isCycle(newX, newY, arr, visited, x,y)
+                    if check:
+                        return True
+        return False
+
+    def containsCycle(self, grid: List[List[str]]) -> bool:
+        N, M = len(grid), len(grid[0])
+        # Initially all the cells are unvisited
+        visited = [[False] * M for _ in range(N)]
+
+        # Variable to store the result
+        cycle = False
+
+        # As there is no fixed position of the cycle
+        # we have to loop through all the elements
+        for i in range(N):
+            if cycle == True:
+                break
+
+            for j in range(M):
+                ## Taking (-1, -1) as source node's parent
+                if visited[i][j] == False:
+                    cycle = self.isCycle(i, j, grid, visited, -1, -1)
+
+                if cycle == True:
+                    break
+
+        return cycle
+
+
+
+
+