Maximum value's random index

最新推荐文章于 2023-02-08 15:58:40 发布

原创最新推荐文章于 2023-02-08 15:58:40 发布 · 363 阅读

0 ·

CC 4.0 BY-SA版权

Multiple Passes 同时被 2 个专栏收录

85 篇文章

订阅专栏

Facebook

39 篇文章

订阅专栏

本文介绍了一种从数组中随机选取最大值索引的方法。首先遍历数组找到最大值及其出现次数，然后生成一个随机数作为最大值的第几次出现，并再次遍历数组返回该次出现的最大值的索引。

#include <vector>
#include <iostream>
#include <cstdlib>
#include <climits>
#include <time.h>
using namespace std;

// naive method
// Go through the array once, find the max and the number of occurrences (n)
// Generate a random number (r) between 1 and n
// Go through the array again, return rth occurrance.
int randomIndex(vector<int>& nums) {
  int max_val = INT_MIN;
  int count = 0;
  for(int i = 0; i < nums.size(); ++i) {
    if(nums[i] > max_val) {
      max_val = nums[i];
      count = 1;
    } else if(nums[i] == max_val) {
      count++;
    }
  }
  srand(time(NULL));
  int random_value = rand() % count + 1;
  cout << random_value << endl;
  cout << "random value is" << endl;
  int max_index = 1;
  for(int i = 0; i < nums.size(); ++i) {
    if(nums[i] == max_val && max_index == random_value) {
      return i;
    } else if(nums[i] == max_val) max_index++;
  }
}

int main(void) {
  vector<int> nums{2, 1, 2, 1, 5, 4, 5, 5};
  cout << randomIndex(nums) << endl;
}