$(function() {
var nums = [2, 3, 4, 5, 6, 9, 10, 18, 17];
var idx = half_search_arr(nums, 4);
alert(idx);
});
var index = -1;
function half_search_arr(arr, num) {
var idx = half_search(arr, 0, arr.length - 1, num);
return idx;
}
function half_search(arr, start, end, num) {
if (arr[start] > num || arr[end] < num) {
return -1;
}
var half = (end - start) / 2;
if (arr[half] == num) {
index = half;
return (end - start) / 2;
} else if (arr[half] > num) {
half_search(arr, start, half, num);
} else if (arr[half] < num) {
half_search(arr, half, end, num);
}
}