Problem
Return the sum of each row of the grid, in row order.
Implement row_sums(grid).
Input
grid: A list of rows of integers.
Output
Return one total per row.
Constraints
0 ≤ rows ≤ 1,000; 0 ≤ values per row ≤ 1,000
Examples
Example 1
Input:
grid = [
[1, 2, 3],
[4, 5, 6]
]
Expected output:
expected = [6, 15]Input:
std::vector<std::vector<long long>> grid = {
{1, 2, 3},
{4, 5, 6}
};
Expected output:
std::vector<long long> expected = {6, 15};Input:
long[][] grid = new long[][] {
new long[] {1, 2, 3},
new long[] {4, 5, 6}
};
Expected output:
long[] expected = new long[] {6, 15};Explanation
1+2+3 = 6 and 4+5+6 = 15: [6, 15].
Example 2
Input:
grid = [
[],
[7]
]
Expected output:
expected = [0, 7]Input:
std::vector<std::vector<long long>> grid = {
{},
{7}
};
Expected output:
std::vector<long long> expected = {0, 7};Input:
long[][] grid = new long[][] {
new long[] {},
new long[] {7}
};
Expected output:
long[] expected = new long[] {0, 7};Explanation
An empty row adds up to 0: [0, 7].
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Each output value comes from one row of the grid.
Hint 2
Sum the numbers in each row independently and keep the results in order.
Hint 3
An empty grid should produce an empty result.
Expected complexity
O(total values) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.