43 lines
1.4 KiB
JavaScript
43 lines
1.4 KiB
JavaScript
|
/*---------------------------------------------------------------------------------------------
|
||
|
|
* Copyright (c) Microsoft Corporation. All rights reserved.
|
||
|
|
* Licensed under the MIT License. See License.txt in the project root for license information.
|
||
|
|
*--------------------------------------------------------------------------------------------*/
|
||
|
|
/**
|
||
|
|
* Takes a sorted array and a function p. The array is sorted in such a way that all elements where p(x) is false
|
||
|
|
* are located before all elements where p(x) is true.
|
||
|
|
* @returns the least x for which p(x) is true or array.length if no element fullfills the given function.
|
||
|
|
*/
|
||
|
|
export function findFirst(array, p) {
|
||
|
|
let low = 0, high = array.length;
|
||
|
|
if (high === 0) {
|
||
|
|
return 0; // no children
|
||
|
|
}
|
||
|
|
while (low < high) {
|
||
|
|
let mid = Math.floor((low + high) / 2);
|
||
|
|
if (p(array[mid])) {
|
||
|
|
high = mid;
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
low = mid + 1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return low;
|
||
|
|
}
|
||
|
|
export function binarySearch(array, key, comparator) {
|
||
|
|
let low = 0, high = array.length - 1;
|
||
|
|
while (low <= high) {
|
||
|
|
const mid = ((low + high) / 2) | 0;
|
||
|
|
const comp = comparator(array[mid], key);
|
||
|
|
if (comp < 0) {
|
||
|
|
low = mid + 1;
|
||
|
|
}
|
||
|
|
else if (comp > 0) {
|
||
|
|
high = mid - 1;
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
return mid;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return -(low + 1);
|
||
|
|
}
|