PAT 1002 A+B for Polynomials python解法

1002 A+B for Polynomials （25 分）
This time, you are supposed to find A+B where A and B are two polynomials.
Input Specification:
Each input file contains one test case. Each case occupies 2 lines, and each line contains the information of a polynomial:
K N​1​​ a​N​1​​​​ N​2​​ a​N​2​​​​ … N​K​​ a​N​K​​​​
where K is the number of nonzero terms in the polynomial, N​i​​ and a​N​i​​​​ (i=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤10，0≤N​K​​<⋯ Output Specification:
For each test case you should output the sum of A and B in one line, with the same format as the input. Notice that there must be NO extra space at the end of each line. Please be accurate to 1 decimal place.
Sample Input:
2 1 2.4 0 3.2
2 2 1.5 1 0.5

Sample Output:
3 2 1.5 1 2.9 0 3.2

a1 = list(input().split())
a2 = list(input().split())
D1 = {}
D2 = {}
D3 = {}
key = []
for i in range(1,len(a1),2):
    D1[int(a1[i])] = float(a1[i+1])
for i in range(1,len(a2),2):
    D2[int(a2[i])] = float(a2[i+1])

for k1,v1 in D1.items():
    for k2,v2 in D2.items():
        if k1 == k2:
            key.append(int(k1))
            if (v1+v2)!=0.0:
                D3[k1] = v1+v2
for i in range(len(key)):
    r1 = D1.pop(key[i])
    r2 = D2.pop(key[i])

D3.update(D1)
D3.update(D2)
L=sorted(D3)[::-1]
#print(D3)
out = []
out.append(str(len(D3)))
for i in L:
    out.append(str(i))
    out.append(str(round(D3[i], 1)))
print(' '.join(out))