我实现二进制搜索算法有什么问题

Question

I am trying to fix the one task from Coursera regarding Binary Search Algorithm. When I am testing my solution it works well. But the Autograder of Coursera is not accepting my solution and throwing that . What am I missing ?

Failed case #17/36: Wrong answer

(Time used: 0.06/5.00, memory used: 46239744/536870912.)

The task Input Format -- The first line of the input contains an integer n and a sequence a0 < a1 < ... < an−1 of n pairwise distinct positive integers in increasing order. The next line contains an integer k and k positive integers b0,b1,...,bk−1.

Constraints -- 1 ≤ n,k ≤ 10^4; 1 ≤ a[i] ≤ 10^9 for all 0 ≤ i < n; 1 ≤ b[]j ≤ 10^9 for all 0 ≤ j < k;

Output Format -- For all i from 0 to k−1, output an index 0 ≤ j ≤ n−1 such that aj = bi or −1 if there is no such index.

Sample 1.

Input:

5

1 5 8 12 13

5

8 1 23 1 11

Output:

2 0 -1 0 -1

In this sample, we are given an increasing sequence 𝑎0 = 1, 𝑎1 = 5, 𝑎2 = 8, 𝑎3 = 12, 𝑎4 = 13 of length five and five keys to search: 8, 1, 23, 1, 11. We see that 𝑎2 = 8 and 𝑎0 = 1, but the keys 23 and 11 do not appear in the sequence 𝑎. For this reason, we output a sequence 2, 0,−1, 0,−1.

My solution

function implemenetBinary(firstArray, secondArray) {
  var locationArray = [];
  for (let i = 0; i < secondArray.length; i++) {
    let value = secondArray[i];
    locationArray[i] = binarySearch(firstArray, value);
  }
  console.log(...locationArray);
  return locationArray;
}

function binarySearch(arr, val) {
  let start = 0;
  let end = arr.length - 1;

  while (start <= end) {
    let mid = Math.floor((start + end) / 2);

    if (arr[mid] === val) {
      return mid;
    }

    if (val < arr[mid]) {
      end = mid - 1;
    } else {
      start = mid + 1;
    }
  }
  return -1;
}


var readline = require("readline");

process.stdin.setEncoding("utf8");
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false,
});

rl.on("line", readLine);

let inputLines = [];

function readLine(line) {
  inputLines.push(line.toString().split(" ").map(Number));
  if (inputLines.length == 4) {
    implemenetBinary(inputLines[1], inputLines[3]);
  }
}

Answer 1

Your binary search is fine.

Your input processing is broken on the empty lines you can get when n or k are 0.