Problema
Build a number triangle: row i (counting from 1) lists the numbers 1, 2, …, i.
Implement number_triangle(rows).
Input
rows: The number of rows.
Output
Return the triangle as a list of rows.
Vincoli
0 ≤ rows ≤ 30
Esempi
Esempio 1
Input:
rows = 3
Output atteso:
expected = [
[1],
[1, 2],
[1, 2, 3]
]Input:
long long rows = 3;
Output atteso:
std::vector<std::vector<long long>> expected = {
{1},
{1, 2},
{1, 2, 3}
};Input:
long rows = 3;
Output atteso:
long[][] expected = new long[][] {
new long[] {1},
new long[] {1, 2},
new long[] {1, 2, 3}
};Spiegazione
Rows are [1], [1, 2] and [1, 2, 3].
Esempio 2
Input:
rows = 0
Output atteso:
expected = []Input:
long long rows = 0;
Output atteso:
std::vector<std::vector<long long>> expected = {};Input:
long rows = 0;
Output atteso:
long[][] expected = new long[][] {};Spiegazione
No rows were requested, so the triangle is empty.
Come affrontarlo
Prova prima da solo, poi apri un suggerimento alla volta.
Suggerimento 1
Row i should contain the numbers from 1 up to i in order.
Suggerimento 2
Grow each row by one element as you move downward.
Suggerimento 3
When there are no rows, the result should simply be empty.
Complessità attesa
O(rows^2) time, O(rows^2) extra space
Riferimenti
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