javascript - 函数没有给出响应

Question

这是我的代码:

function findTriad(numbers, sum) {
  for (let i = 0; i < numbers.length - 1; i++) {
    const firstNumber = numbers[i];
    const newSum = sum - firstNumber;
    let startOfCheckIndex = i + 1;
    const endOfCheckIndex = numbers.length - 1;

    while (startOfCheckIndex < endOfCheckIndex) {
      const possibleAnswer =
        numbers[startOfCheckIndex] + numbers[endOfCheckIndex];
      if (possibleAnswer === newSum) {
        return [
          numbers[i],
          numbers[startOfCheckIndex],
          numbers[endOfCheckIndex]
        ];
      } else if (sum < newSum) {
        startOfCheckIndex++;
      }
    }
  }
  return ["N/A"];
}

function logFindTriad(numbers, sum) {
  const answer = findTriad(numbers, sum);

  console.log("Sum required: " + sum);
  console.log("Numbers given: " + numbers.join(", "));
  console.log("Found: " + answer.join(", ") + "\n");
}

logFindTriad([10, 15, 3, 7], 20);

有谁知道为什么这段代码没有给我任何值(value)？如果您发现我的代码有任何错误或需要改进的地方，它应该给我返回 [10,3,7]，请告诉我，即使它不能解决问题。

Answer 1

代码第一次输入while (startOfCheckIndex < endOfCheckIndex) {startOfCheckIndex 为 1，endOfCheckIndex 为 3这意味着possibleAnswer是 10 + 7 = 17。newSum 为 10，sum 为 20这意味着两者都没有

if (possibleAnswer === newSum) {

或

} else if (sum < newSum) {

是真的。导致 startOfCheckIndex 永远不会改变。

反过来，while (startOfCheckIndex < endOfCheckIndex) {永远为真，导致无限循环。

您需要添加 else条款或其他一些离职条件。

这是一个演示该问题的示例。

let loopRestriction = 100

function findTriad(numbers, sum) {
  for (let i = 0; i < numbers.length - 1; i++) {
    const firstNumber = numbers[i];
    const newSum = sum - firstNumber;
    let startOfCheckIndex = i + 1;
    const endOfCheckIndex = numbers.length - 1;

    while (startOfCheckIndex < endOfCheckIndex) {

      const possibleAnswer = numbers[startOfCheckIndex] + numbers[endOfCheckIndex];
      if (loopRestriction-- <= 0) {
        console.log("Stuck in while loop for atleast 100 iterations.")
        break
      }
      console.log({
        startOfCheckIndex,
        endOfCheckIndex,
        possibleAnswer,
        sum,
        newSum
      })

      if (possibleAnswer === newSum) {
        return [
          numbers[i],
          numbers[startOfCheckIndex],
          numbers[endOfCheckIndex]
        ];
      } else if (sum < newSum) {
        startOfCheckIndex++;
      }
    }
  }
  return ["N/A"];
}

function logFindTriad(numbers, sum) {
  const answer = findTriad(numbers, sum);

  console.log("Sum required: " + sum);
  console.log("Numbers given: " + numbers.join(", "));
  console.log("Found: " + answer.join(", ") + "\n");
}

logFindTriad([10, 15, 3, 7], 20);