Problème
One move increases one array value by 1. Make the array nondecreasing: each value must be greater than or equal to the one immediately before it. You may not decrease values or reorder them.
Implement increasing_array(numbers).
Input
numbers: The values in their original order.
Output
Return the minimum total number of unit increments.
Contraintes
1 ≤ length ≤ 200,000. Each value is between 1 and 1,000,000,000. Use a signed 64-bit result.
Exemples
Entrée :
numbers = [4, 1, 3]
Sortie attendue :
expected = 4Entrée :
std::vector<long long> numbers = {4, 1, 3};
Sortie attendue :
long long expected = 4;Entrée :
long[] numbers = new long[] {4, 1, 3};
Sortie attendue :
long expected = 4;Explication
Raise 1 to 4 using three moves and 3 to 4 using one move. The result [4, 4, 4] uses four moves.
Entrée :
numbers = [1, 2, 2, 5]
Sortie attendue :
expected = 0Entrée :
std::vector<long long> numbers = {1, 2, 2, 5};
Sortie attendue :
long long expected = 0;Entrée :
long[] numbers = new long[] {1, 2, 2, 5};
Sortie attendue :
long expected = 0;Explication
Every value is already at least the preceding value; equal neighbors are allowed.
Comment l'aborder
Essayez d'abord seul, puis ouvrez les indices un par un.
Indice 1
Scan from left to right, because each value only depends on the previous one.
Indice 2
Whenever a value is too small, raise it just enough to match the running minimum allowed value.
Indice 3
Track the total increments carefully, since earlier increases affect later comparisons.
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.