python 01障碍矩阵，最短路径，最小转弯数, BFS

最短路径

matrix = [[0,0,0],[0,1,0],[0,0,0],[0,1,1],[0,0,0]]
m = len(matrix)
n = len(matrix[0])
res = [[0 for _ in range(n)] for _ in range(m)]
vis = [[0 for _ in range(n)] for _ in range(m)]
sx, sy = 1, 2 #起点
ex, ey = 4, 1 #终点
q = []
q.append([sx,sy,0])
while q:
    x, y, t = q.pop(0)
    for i,j in [[x+1,y], [x-1,y], [x,y+1], [x,y-1]]:
        if 0<=i<m and 0<=j<n and matrix[i][j] == 0 and not vis[i][j]:
            q.append([i,j,t+1])
            vis[i][j] = 1
            res[i][j] = t + 1
print(res[ex][ey])

最小转弯数

matrix = [[0,0,0],[0,1,0],[0,0,0],[0,1,1],[0,0,0]]
m = len(matrix)
n = len(matrix[0])
turn = [[float('inf') for _ in range(n)] for _ in range(m)]
vis = [[0 for _ in range(n)] for _ in range(m)]
sx, sy = 1, 2
ex, ey = 4, 1
q = []
#x,y,direction,turns
q.append([sx, sy,-1,-1])
direction = [[1,0],[-1,0],[0,-1],[0,1]]
vis[sx][sy] = 1
while q:
    node = q.pop(0)
    
    if node[0] == ex and node[1] == ey:
        print(turn[ex][ey])
    for i in range(len(direction)):
        x = direction[i][0] + node[0]
        y = direction[i][1] + node[1]
        
        if x < 0 or x >= m or y < 0 or y >= n:
            continue
        if matrix[x][y] == 1 or vis[x][y]:
            continue
        tmp = node[3]
        if node[2] != i:
            tmp = node[3] + 1
        if tmp <= turn[x][y]:
            turn[x][y] = tmp
            vis[x][y] = 1
            q.append([x, y, i, tmp])