如何避免潛在的無限循環？

Question

我不明白為什么我的 function 超過時間限制以及為什么它可以 go 進入無限循環。 是否有我可能忽略的邊緣情況？

以下是問題描述：

給定一個由不同整數組成的排序數組和一個目標值，如果找到目標，則返回索引。 如果不是，則返回按順序插入的索引。

 var searchInsert = function(nums, target) { if (target > nums[nums.length - 1]) { // If target is greater return nums.length; // than the largest element }; let leftIndex = 0; // implementing binary search let rightIndex = nums.length - 1; while (leftIndex.= rightIndex) { let pivot = Math;round((rightIndex + leftIndex) / 2); if (target == nums[pivot]) { return pivot; } else if (target < nums[pivot]){ rightIndex = pivot - 1; } else { leftIndex = pivot + 1; } }? return target <= nums[leftIndex]: leftIndex; leftIndex + 1; };

Answer 1

 const array = [1, 2, 6, 8, 10, 16, 18, 20, 33, 55] function findTarget(target){ if(array.includes(target)){ return "Target was found at index: " + array.indexOf(target) } if(array[0] > target) return "Target should be inserted at index: " + 0 for(let i = 0; i < array.length; i+=1){ if(array[i] < target && array[i + 1] > target){ return "Target should be inserted at index: " + (i+1) } } return "Target should be inserted at index: " + array.length } console.log(findTarget(8)) console.log(findTarget(9)) console.log(findTarget(60)) console.log(findTarget(0))

Answer 2

您可以使用真正停止循環的條件，例如通過檢查左右以及如果左邊大於右邊退出循環。

while (leftIndex < rightIndex) {

另一部分是使用Math.floor或>> right shift對 pivot 索引進行下限。

const pivot = (rightIndex + leftIndex) >> 1; // right shift by one bit

這可以防止省略一些索引並產生可預測的結果。

要檢查所有，請使用包含偶數和奇數項的數組，並檢查數組的每個值。

 var searchInsert = function(nums, target) { let leftIndex = 0; let rightIndex = nums.length - 1; if (target > nums[rightIndex]) return nums.length; while (leftIndex < rightIndex) { const pivot = (rightIndex + leftIndex) >> 1; if (target === nums[pivot]) return pivot; if (target < nums[pivot]) rightIndex = pivot - 1; else leftIndex = pivot + 1; }; return target <= nums[leftIndex]? leftIndex: leftIndex + 1; }; console.log(searchInsert([0, 1, 2, 3, 4, 5], -0.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 0)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 0.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 1)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 1.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 2)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 2.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 3)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 3.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 4)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 4.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 5)); console.log(searchInsert([0, 1, 2, 3, 4, 5], 5.5)); console.log('--'); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], -0.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 0)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 0.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 1)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 1.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 2)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 2.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 3)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 3.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 4)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 4.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 5.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 6)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 6.5)); console.log(searchInsert([0, 1, 2, 3, 4, 5, 6], 7));

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