Problème
Every neuron starts with the same calculation: multiply each input by its weight and add everything up. That is the dot product of two vectors:
a · b = a₁×b₁ + a₂×b₂ + … + aₙ×bₙ
Implement dot_product(a, b).
Input
a, b: Two lists of numbers with the same length.
Output
Return the dot product as a decimal number.
Contraintes
1 ≤ length of a = length of b ≤ 1,000
-1,000 ≤ each value ≤ 1,000
Exemples
Entrée :
a = [1.0, 2.0, 3.0]
b = [4.0, 5.0, 6.0]
Sortie attendue :
expected = 32.0Entrée :
std::vector<double> a = {1.0, 2.0, 3.0};
std::vector<double> b = {4.0, 5.0, 6.0};
Sortie attendue :
double expected = 32.0;Entrée :
double[] a = new double[] {1.0, 2.0, 3.0};
double[] b = new double[] {4.0, 5.0, 6.0};
Sortie attendue :
double expected = 32.0;Explication
1×4 + 2×5 + 3×6 = 4 + 10 + 18 = 32.
Entrée :
a = [0.5, -1.5]
b = [2.0, 4.0]
Sortie attendue :
expected = -5.0Entrée :
std::vector<double> a = {0.5, -1.5};
std::vector<double> b = {2.0, 4.0};
Sortie attendue :
double expected = -5.0;Entrée :
double[] a = new double[] {0.5, -1.5};
double[] b = new double[] {2.0, 4.0};
Sortie attendue :
double expected = -5.0;Explication
0.5×2 + (-1.5)×4 = 1 - 6 = -5.
Comment l'aborder
Essayez d'abord seul, puis ouvrez les indices un par un.
Indice 1
Multiply matching positions from the two lists and combine the results into one total.
Indice 2
A single pass is enough because each pair contributes independently to the final value.
Indice 3
Make sure the lists have the same length, and keep the accumulator in a numeric type that preserves decimals if needed.
Complexité attendue
O(n) time, O(1) extra space
Références
Ce défi a été adapté pour CodeUtility. Suivez l'énoncé et les contraintes ci-dessus.