Question

有关Dijkstra算法的帮助。任务的本质：找到最可能的方法是必要的。这里使用概率乘法。输入： 100, 9900, 1, 100（顶点数，圆弧数，起始顶点和终止顶点） 1, 2, 0.3（起始顶点，终止顶点和通过路径的概率） ...

我的结果：

35, 35, 3, 54, 98, 100 (most likely successful path)
0.9577 (probability of passage).

正确的结果：

1, 92, 35, 3, 54, 98, 100
0.9577

我认为这部分代码无法正常工作（构建最短路径）：

 while (i!=0):
            for j in range(end, -1, -1):
                if (ves[i]!=0.0 and round(weight[i] / ves[i],6) == weight[j] and i<=test):
                    result.append(j+1)
                    test=j
            i -= 1

整个代码：

def Dijkstra(N, S, matrix, end):
    valid = [True] * N
    weight = [0.01] * N
    weight[S] = 1.0
    ves=[0.0]*N
    result=[]
    for i in range(N):
        min_weight = 0.0
        ID_min_weight = 0.0
        for i in range(len(weight)):
            if valid[i] and weight[i] > min_weight:
                min_weight = weight[i]
                ID_min_weight = i
        for i in range(N):
            if (round(weight[ID_min_weight] * matrix[ID_min_weight][i],6) > weight[i] and i<end+1):
                weight[i] = round(weight[ID_min_weight] * matrix[ID_min_weight][i],6)
                ves[i]=matrix[ID_min_weight][i]
        valid[ID_min_weight] = False

    result.append(end + 1)
    i = end
    test = end
    while (i!=0):
        for j in range(end, -1, -1):
            if (ves[i]!=0.0 and round(weight[i] / ves[i],6) == weight[j] and i<=test):
                result.append(j+1)
                test=j
        i -= 1


    result.reverse()
    print (*result)

    return round(weight[end],4)

str=[]
matrix2=[]
for i in input().split():
    str.append(int(i))

N = str[0]   
M = str[1]   
begin = str[2]  
end = str[3]    

matrix = [[float (j) for j in input().split()] for i in range(M)]

for i in matrix:
    if len(i)>3:
        exit()

for i in range(N):
    matrix2.append([])
    for j in range(N):
        matrix2[i].append(0.01)

for i in range(M):
    matrix2[int(matrix[i][0]-1)][int(matrix[i][1]-1)] = matrix[i][2]

print(Dijkstra(N, begin-1, matrix2,end-1))

Dijkstra算法实施中的错误

0 个答案: