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from collections import deque def is_valid(x, y, m, n): return 0 <= x < m and 0 <= y < n def bfs(forest, m, n, x, y): dx = [-1, -1, -1, 0, 0, 1, 1, 1] dy = [-1, 0, 1, -1, 1, -1, 0, 1] visited = [[False]*n for _ in range(m)] queue = deque([(x, y, 0)]) visited[x][y] = True max_time = 0 while queue: x, y, time = queue.popleft() max_time = max(max_time, time) for i in range(8): nx, ny = x + dx[i], y + dy[i] if is_valid(nx, ny, m, n) and not visited[nx][ny] and forest[nx][ny] == 'T': queue.append((nx, ny, time + 1)) visited[nx][ny] = True return max_time m, n = map(int, input().split()) x, y = map(int, input().split()) x -= 1 y -= 1 forest = [list(input()) for _ in range(m)] print(bfs(forest, m, n, x, y)) make the code pass these 2 test cases: Input 3 3 1 3 W W T W W W W W W Output 1 Your output 0 Input 3 3 1 3 W T T T W W W T T Output 5 Your output 0

Question

from collections import deque

def is_valid(x, y, m, n): return 0 <= x < m and 0 <= y < n

def bfs(forest, m, n, x, y): dx = [-1, -1, -1, 0, 0, 1, 1, 1] dy = [-1, 0, 1, -1, 1, -1, 0, 1] visited = [[False]*n for _ in range(m)] queue = deque([(x, y, 0)]) visited[x][y] = True max_time = 0 while queue: x, y, time = queue.popleft() max_time = max(max_time, time) for i in range(8): nx, ny = x + dx[i], y + dy[i] if is_valid(nx, ny, m, n) and not visited[nx][ny] and forest[nx][ny] == 'T': queue.append((nx, ny, time + 1)) visited[nx][ny] = True return max_time

m, n = map(int, input().split()) x, y = map(int, input().split()) x -= 1 y -= 1 forest = [list(input()) for _ in range(m)] print(bfs(forest, m, n, x, y))

make the code pass these 2 test cases: Input 3 3 1 3 W W T W W W W W W Output 1 Your output 0

Input 3 3 1 3 W T T T W W W T T Output 5 Your output 0

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Solution

The problem with your code is that you are only considering the cells with 'T' as valid cells to move to. However, from the problem statement, it seems like you can move to any cell, but you only count the time when you move to a cell with a 'T'.

Here is the corrected code:

from collections import deque

def is_valid(x, y, m, n):
    return 0 <= x < m and 0 <= y < n

def bfs(forest, m, n, x, y):
    dx = [-1, -1, -1, 0, 0, 1, 1, 1]
    dy = [-1, 0, 1, -1, 1, -1, 0, 1]
    visited = [[False]*n for _ in range(m)]
    queue = deque([(x, y, 0)])
    visited[x][y] = True
    max_time = 0
    while queue:
        x, y, time = queue.popleft()
        if forest[x][y] == 'T':
            max_time = max(max_time, time)
        for i in range(8):
            nx, ny = x + dx[i], y + dy[i]
            if is_valid(nx, ny, m, n) and not visited[nx][ny]:
                queue.append((nx, ny, time + 1 if forest[nx][ny] == 'T' else time))
                visited[nx][ny] = True
    return max_time

m, n = map(int, input().split())
x, y = map(int, input().split())
x -= 1
y -= 1
forest = [list(input()) for _ in range(m)]
print(bfs(forest, m, n, x, y))

In this corrected code, we are considering all cells as valid cells to move to. However, we only increment the time when we move to a cell with a 'T'. This is done by changing the line where we append to the queue to queue.append((nx, ny, time + 1 if forest[nx][ny] == 'T' else time)). This means that if the next cell is a 'T', we increment the time, otherwise we keep the same time.

This problem has been solved

Similar Questions

code: from collections import dequedef bfs(graph, start, end): visited = set() queue = deque([(start, [start])]) while queue: current, path = queue.popleft() if current == end: return path if current not in visited: visited.add(current) for neighbor in graph[current]: queue.append((neighbor, path + [neighbor])) return None graph = { 0: [3], 1: [0, 2, 4], 2: [7], 3: [4, 5], 4: [3, 6], 5: [6], 6: [7]} start_node = 0 end_node = 7 path = bfs(graph, start_node, end_node)if path: print(f"Path from node {start_node} to node {end_node}: {path}")else: print(f"No path found from node {start_node} to node {end_node}") error: from collections import dequedef bfs(graph, start, end): visited = set() queue = deque([(start, [start])]) while queue: current, path = queue.popleft() if current == end: return path if current not in visited: visited.add(current) for neighbor in graph[current]: queue.append((neighbor, path + [neighbor])) return None graph = { 0: [3], 1: [0, 2, 4], 2: [7], 3: [4, 5], 4: [3, 6], 5: [6], 6: [7]} start_node = 0 end_node = 7 path = bfs(graph, start_node, end_node)if path: print(f"Path from node {start_node} to node {end_node}: {path}")else: print(f"No path found from node {start_node} to node {end_node}") fix the bug

A list of elements in which enqueue operation takes place from one end, and dequeue operation takes place from one end is__a.Binary treeb.Stackc.Queued.Linked list

You are roaming in a forest. This forest can be viewed as a graph with n nodes and m undirected edges. You roam the forest by traveling through the undirected edges from one node to another. You want to travel all the nodes at least once and stop when you have visited every node. Given that this is a connected graph, find the smallest lexicographical sequence of nodes that can be visited and return it in an array.The m undirected edges are given in the form of two arrays a and b, wherein there is an undirected edge between a[i] and b[i].Input FormatThe first line contains n, the number of nodes in the forest.The second line contains m, the number of edges in the forest.The next m lines contain the elements of the array a.The next line contains m, the number of edges in the forest.The next m lines contain the elements of the array b.Constraints2 <= n <= 1051 <= m <= 105The graph is a single connected component.If i!=j then (a[i], b[i]) != (a[j], b[j])Output FormatReturn an array denoting the lexicographically smallest sequence in which the nodes can be visited.

If vertices 2, 3 and 4 are added in the queue in the given order during the BFS visit, which vertex will be marked as visited first? Vertex 2 will be marked as visited first. Vertex 3 will be marked as visited first. Vertex 4 will be marked as visited first. None of the three given vertices will be marked as visited first.

Write an algorithm for Breadth First Search (BFS) traversal of a graph.

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