ACM算法作业

1. 矩阵乘法

# dynamic_progressing
import random
A_list = [(7, 9), (9, 7), (7, 7), (7, 13), (13, 15), (15, 14), (14, 5), (5, 8), (8, 13), (13, 14)]
# for i in range(10):
#     A_list.append((A_list[-1][1],random.randint(5,15)))
print(A_list)
m = [[-1]*10 for i in range(10)]
def mul_times(matrix,i,j,A_list):
    if i==j:
        matrix[i][j]=0
        return matrix
    else:
        for k in range(i,j):
            if matrix[i][k]==-1:
                matrix = mul_times(matrix,i,k,A_list)
            if matrix[k+1][j]==-1:
                matrix = mul_times(matrix,k+1,j,A_list)
        num =min([matrix[i][k]+matrix[k+1][j]+A_list[i][0]*A_list[k][1]*A_list[j][1] for k in range(i,j)])
        matrix[i][j] = int(num)
        print("0",i,j,matrix)
    return matrix

for i in range(len(A_list)):
    for j in range(i,len(A_list)):
        m = mul_times(m,i,j,A_list)
    print(m)