Histogramming

题面

Write a GPU program that computes the histogram of an array of 32-bit integers. Count occurrences for values in [0, num_bins) into a length num_bins integer array.

Implementation Requirements

• Use only native features (external libraries are not permitted)
• The solve function signature must remain unchanged
• The final result must be stored in the histogram array

Examples

Input: input = [0, 1, 2, 1, 0], N = 5, num_bins = 3
Output: [2, 2, 1]

Input: input = [3, 3, 3, 3], N = 4, num_bins = 5
Output: [0, 0, 0, 4, 0]

Constraints

• 1 ≤ N ≤ 100,000,000
• 0 ≤ input[i] < num_bins
• 1 ≤ num_bins ≤ 1024
• Performance is measured with N = 50,000,000, num_bins = 256