frequency

I just finished writing an algorithm that finds values in an input integer array with max/min occurrences. My idea is to sort the array (all the occurrences are now in sequence) and use a <value:occurrences> pair to store for every value the number of occurrences correspondent. It should be O(nlogn) complexity but I think that there are some constant multipliers. What can I do to improve performance? #include <stdio.h> #include <stdlib.h> #include "e7_8.h" #define N 20 /*Structure for <value, frequencies_count> pair*/ typedef struct { int value; int freq; } VAL_FREQ; void get_freq(int *v, int

I have a large array A of size [0, 8388608] of "relatively small" integers A[i] = [0, 131072] and I want to find the most frequently occurring element of every N=32 elements. What would be faster, A. Create an associative array B of size 131072, iterate through 32 elements, increment B[A[i]], then iterate through B, find the largest value, reset all elements in B to 0, repeat |A|/32 times. B. qsort every 32 elements, find the largest range where A[i] == A[i-1] (and thus the most frequent element), repeat |A|/32 times. (EDIT) C. Something else. An improvement over the first approach is possible

前几天看了看博客，从16年底到现在，3年了，终于看书到第9章了。都怪自己愚钝不堪，唯有吃苦努力，一点一点一页一页慢慢啃了。 代码： %% ------------------------------------------------------------------------ %% Output Info about this m-file fprintf('\n***********************************************************\n'); fprintf(' <DSP using MATLAB> Problem 9.2 \n\n'); banner(); %% ------------------------------------------------------------------------ % ------------------------------------------------------------ % PART 1 % ------------------------------------------------------------ % Discrete time signal n1_start = 0; n1_end = 60; n1 = [n1_start:1:n1_end]; xn1