题解 | #数字在升序数组中出现的次数#

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param nums int整型一维数组 
 * @param k int整型 
 * @return int整型
 */
export function GetNumberOfK(nums: number[], k: number): number {
    // write code here
    let n = 0

    function findNum(arr, k) {
        if(arr.length === 0) return
        
        let pivotIndex = Math.floor(arr.length / 2)
        let pivot = arr[pivotIndex]
        let left = arr.slice(0, pivotIndex), right = arr.slice(pivotIndex + 1, arr.length)
        if(k < pivot) { return findNum(left, k) }
        else if(k > pivot) { return findNum(right, k) }
        else if(k === pivot) { 
            n++
            findNum(left, k) 
            findNum(right, k)
        }
    }

    findNum(nums, k)

    return n
}