Условие
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.
Ограничения
1 ≤ length ≤ 200,000. Each value is between 1 and 1,000,000,000. Use a signed 64-bit result.
Примеры
Ввод:
numbers = [4, 1, 3]
Ожидаемый вывод:
expected = 4Ввод:
std::vector<long long> numbers = {4, 1, 3};
Ожидаемый вывод:
long long expected = 4;Ввод:
long[] numbers = new long[] {4, 1, 3};
Ожидаемый вывод:
long expected = 4;Пояснение
Raise 1 to 4 using three moves and 3 to 4 using one move. The result [4, 4, 4] uses four moves.
Ввод:
numbers = [1, 2, 2, 5]
Ожидаемый вывод:
expected = 0Ввод:
std::vector<long long> numbers = {1, 2, 2, 5};
Ожидаемый вывод:
long long expected = 0;Ввод:
long[] numbers = new long[] {1, 2, 2, 5};
Ожидаемый вывод:
long expected = 0;Пояснение
Every value is already at least the preceding value; equal neighbors are allowed.
Как подступиться
Сначала попробуйте сами, затем открывайте подсказки по одной.
Подсказка 1
Scan from left to right, because each value only depends on the previous one.
Подсказка 2
Whenever a value is too small, raise it just enough to match the running minimum allowed value.
Подсказка 3
Track the total increments carefully, since earlier increases affect later comparisons.
Ожидаемая сложность
O(n) time, O(1) extra space
Ссылки
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