Python 0/1背包问题

def knapsack(i, capacity):
    if n == 1:
        dp[i] = 1
        return
    if v_all[i][capacity] == -1:
        if i == 0 or capacity == 0:
            v_all[i][capacity] = 0
        elif s[i] > capacity:
            v_all[i][capacity] = 0
            knapsack(i - 1, capacity)
        else:
            s1 = knapsack(i - 1, capacity - s[i]) + v[i]
            s2 = knapsack(i - 1, capacity)
            if s1 >= s2:
                dp[i] = 1
                v_all[i][capacity] = s1
            else:
                dp[i] = 0
                v_all[i][capacity] = s2
    return v_all[i][capacity]
 
 
n = 5
v = [100, 200, 300, 150, 120]
s = [300, 200, 150, 200, 100]
capacity = 500
dp = [0] * n
v_all = []
for i in range(n):
    temp = [-1] * (capacity + 1)
    v_all.append(temp)
knapsack(n - 1, capacity)
print(dp)