如何在列表球拍的正确位置插入数字？

function binarySearchInsert(arr, num) {
    let left = 0;
    let right = arr.length - 1;

    while (left <= right) {
        let mid = Math.floor((left + right) / 2);
        if (arr[mid] === num) {
            return mid; // 如果找到相同的数字，直接返回索引
        } else if (arr[mid] < num) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }

    // 插入位置为 left
    arr.splice(left, 0, num);
    return left;
}

// 示例用法
let list = [1, 3, 5, 7, 9];
let numberToInsert = 4;
let index = binarySearchInsert(list, numberToInsert);
console.log(`Inserted ${numberToInsert} at index ${index}`);
console.log(list); // 输出: [1, 3, 4, 5, 7, 9]