题解 | #查找数组元素位置#
查找数组元素位置
http://www.nowcoder.com/practice/e7835a8113dd48afb15f77ef8d1dcb1d
二分查找方法
其时间复杂度: O(log2n)
function indexOf(arr, item) {
let left = 0,
mid,
right = arr.length - 1;
while(left <= right) {
mid = parseInt((left + right) / 2)
if(item == arr[mid]) {
return mid
} else if(item > arr[mid]) {
left = mid + 1
} else {
right = mid - 1
}
}
return -1
}
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