Problema
The decorator pattern adds behaviour by wrapping an object in layers. Each layer here changes the price of the layer inside it.
Start from base_price and apply the decorators in order:
discount p: reduce the price by p percent.tax p: increase the price by p percent.shipping a: add a fixed amount a.coupon a: subtract a, but never go below 0.
Implement price_decorators(base_price, decorators).
Input
base_price: The starting price.
decorators: The layers, in the order they wrap the price. Amounts may have decimals.
Output
Return the final price. Answers within 1e-6 are accepted.
Vincoli
0 ≤ base_price ≤ 1,000,000
0 ≤ number of decorators ≤ 100; 0 ≤ p ≤ 100, 0 ≤ a ≤ 100,000
Esempi
Input:
base_price = 100
decorators = ["discount 10", "tax 8", "shipping 5"]
Output atteso:
expected = 102.2Input:
long long base_price = 100;
std::vector<std::string> decorators = {"discount 10", "tax 8", "shipping 5"};
Output atteso:
double expected = 102.2;Input:
long base_price = 100;
string[] decorators = new string[] {"discount 10", "tax 8", "shipping 5"};
Output atteso:
double expected = 102.2;Spiegazione
100 − 10% = 90, plus 8% tax = 97.2, plus 5 shipping = 102.2.
Input:
base_price = 20
decorators = ["coupon 25", "shipping 4"]
Output atteso:
expected = 4.0Input:
long long base_price = 20;
std::vector<std::string> decorators = {"coupon 25", "shipping 4"};
Output atteso:
double expected = 4.0;Input:
long base_price = 20;
string[] decorators = new string[] {"coupon 25", "shipping 4"};
Output atteso:
double expected = 4.0;Spiegazione
The coupon would take the price below zero, so it stops at 0; shipping then makes it 4.
Come affrontarlo
Prova prima da solo, poi apri un suggerimento alla volta.
Suggerimento 1
Apply the layers strictly in the given order.
Suggerimento 2
Percentages are taken from the current price, not the base price.
Suggerimento 3
A coupon can never push the price below 0.
Complessità attesa
O(number of decorators) time, O(1) extra space
Riferimenti
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