JavaScript 计算数组中的正数和负数程序

给定一个数字数组。编写一个JavaScript程序来查找数组中的正数和负数。

例子：

输入： numbers_array1= [10,20, -1,22,99,20, -9]

输出： 正数个数=5，负数个数=2

输入： numbers_array2= [-121, – 78, -13, 54, -23]

输出： 正数个数=1，负数个数=4

例子 1： 这段代码使用JavaScript从给定的数组中计算正数和负数。使用for循环遍历列表中的每个元素，并检查是否符合条件(num >= 0)，这是检查负数的条件。如果满足条件，则增加负数计数，否则增加正数计数。

JavaScript

<script>    
    var numbers=[10,-12,89,56,-83,8,90,-8]
    var pos_count=neg_count=0
    for(let i=0;i<numbers.length;i++)
    {
      if (numbers[i]<0)
       neg_count++;
      else
       pos_count++;
    }
    console.log(`The positive numbers in an array is {pos_count}`)
    console.log(`The negative numbers in an array is{neg_count}`)
</script>

输出

The positive numbers in an array is 5
The negative numbers in an array is 3

示例2 : 下面的代码使用JavaScript的while循环。

Javascript

<script>   
    var numbers=[7,-8,55,-87,28,74,-21,54,4]
    var pos_count=neg_count=i=0
    while(i<numbers.length)
    {
      if (numbers[i]<0)
       neg_count++;
      else
       pos_count++;
      i++;
    }
    console.log(`The positive numbers in an array is {pos_count}`)
    console.log(`The negative numbers in an array is{neg_count}`)
</script>

输出

The positive numbers in an array is 6
The negative numbers in an array is 3

示例 3 ：以下代码使用JavaScript，使用 forEach 循环

Javascript

var numbers=[-8,10,23,44,-80,-15,-13,-1]
var pos_count=neg_count=0
numbers.forEach(element => {
  if (element<0)
   neg_count++;
  else
   pos_count++;
});
console.log(`The positive numbers in an array is {pos_count}`)
console.log(`The negative numbers in an array is{neg_count}`)

输出

The positive numbers in an array is 3
The negative numbers in an array is 5

例子4：使用map方法

Javascript

var numbers=[10,-12,89,56,-83,8,90,-8]
var pos_count=neg_count=0
numbers.map(function(element)
{
  if (element<0)
   neg_count++;
  else
   pos_count++;
});
console.log(`The positive numbers in an array is {pos_count}`)
console.log(`The negative numbers in an array is{neg_count}`)

输出

The positive numbers in an array is 5
The negative numbers in an array is 3

示例5： 使用递归

JavaScript

function countNumbers(numbers, index, pos_count, neg_count) {
    if (index < numbers.length) {
        if (numbers[index] < 0) {
            neg_count++;
        } else {
            pos_count++;
        }
        return countNumbers(numbers, index + 1, pos_count, neg_count);
    } else {
        return { pos_count, neg_count };
    }
}
 
var numbers=[-8,10,23,44,-80,-15,-1]
var counts = countNumbers(numbers, 0, 0, 0);
console.log(`The positive numbers in an array is {counts.pos_count}`)
console.log(`The negative numbers in an array is{counts.neg_count}`)

输出

The positive numbers in an array is 3
The negative numbers in an array is 4

高效代码:-

这个代码更高效，因为它消除了递归和随之而来的函数调用的需要，而是使用一个简单的for循环来遍历数组。这应该导致更快的执行和更少的内存使用。

JavaScript

function countNumbers(numbers) {
    let pos_count = 0;
    let neg_count = 0;
 
    for (let i = 0; i < numbers.length; i++) {
        if (numbers[i] < 0) {
            neg_count++;
        } else {
            pos_count++;
        }
    }
    return { pos_count, neg_count };
}
 
var numbers = [-8, 10, 23, 44, -80, -15, -1]
              var counts = countNumbers(numbers);
console.log(`The positive numbers in an array is {counts.pos_count}`)
console.log(`The negative numbers in an array is {counts.neg_count}`)

C++

#include <iostream>
using namespace std;
 
struct Counts {
    int pos_count;
    int neg_count;
};
 
Counts countNumbers(int numbers[], int size) {
    Counts counts = {0, 0};
    for (int i = 0; i < size; i++) {
        if (numbers[i] < 0) {
            counts.neg_count++;
        } else {
            counts.pos_count++;
        }
    }
    return counts;
}
 
int main() {
    int numbers[] = {-8, 10, 23, 44, -80, -15, -1};
    int size = sizeof(numbers) / sizeof(numbers[0]);
    Counts counts = countNumbers(numbers, size);
    cout << "The positive numbers in an array is " << counts.pos_count << endl;
    cout << "The negative numbers in an array is " << counts.neg_count << endl;
    return 0;
}

Java

class Main {
    static class Counts {
        int pos_count;
        int neg_count;
    }
 
    static Counts countNumbers(int[] numbers) {
        Counts counts = new Counts();
        counts.pos_count = 0;
        counts.neg_count = 0;
        for (int i = 0; i < numbers.length; i++) {
            if (numbers[i] < 0) {
                counts.neg_count++;
            } else {
                counts.pos_count++;
            }
        }
        return counts;
    }
 
    public static void main(String[] args) {
        int[] numbers = {-8, 10, 23, 44, -80, -15, -1};
        Counts counts = countNumbers(numbers);
        System.out.println("The positive numbers in an array is " + counts.pos_count);
        System.out.println("The negative numbers in an array is " + counts.neg_count);
    }
}

C

using System;
 
class MainClass {
    struct Counts {
        public int pos_count;
        public int neg_count;
    }
    public static Counts countNumbers(int[] numbers) {
        Counts counts = new Counts { pos_count = 0, neg_count = 0 };
        for (int i = 0; i < numbers.Length; i++) {
            if (numbers[i] < 0) {
                counts.neg_count++;
            } else {
                counts.pos_count++;
            }
        }
        return counts;
    }
    public static void Main(string[] args) {
        int[] numbers = new int[] {-8, 10, 23, 44, -80, -15, -1};
        Counts counts = countNumbers(numbers);
        Console.WriteLine("The positive numbers in an array is " + counts.pos_count);
        Console.WriteLine("The negative numbers in an array is " + counts.neg_count);
    }
}

输出

The positive numbers in an array is {counts.pos_count}
The negative numbers in an array is {counts.neg_count}

示例 7：使用 Array.prototype.filter() 方法过滤掉正数和负数

Javascript

// defining the array of numbers
var numbers=[-8,10,23,44,-80,-15,-13,-1]
 
// creating a new array containing only positive numbers using filter method
var positiveNumbers = numbers.filter(function(number) {
  // return only numbers greater than or equal to 0
  return number >= 0;
});
 
// creating a new array containing only negative numbers using filter method
var negativeNumbers = numbers.filter(function(number) {
  // return only numbers less than 0
  return number < 0;
});
 
// printing the count of positive numbers in the array
console.log(`The positive numbers in an array is {positiveNumbers.length}`)
 
// printing the count of negative numbers in the array
console.log(`The negative numbers in an array is{negativeNumbers.length}`)

输出

The positive numbers in an array is 3
The negative numbers in an array is 5

时间复杂度: O(n)

辅助空间复杂度: O(n)