63 lines
1.5 KiB
JavaScript
63 lines
1.5 KiB
JavaScript
export function binarySearch(arr, cmp) {
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let min = 0;
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let max = arr.length - 1;
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while (min <= max) {
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let mid = (min + max) >> 1;
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let res = cmp(arr[mid]);
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if (res < 0) {
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max = mid - 1;
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} else if (res > 0) {
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min = mid + 1;
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} else {
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return mid;
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}
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}
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return -1;
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}
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export function range(index, end) {
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let range = [];
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while (index < end) {
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range.push(index++);
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}
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return range;
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}
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export const asciiDecoder = new TextDecoder('ascii');
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// Based on https://github.com/niklasvh/base64-arraybuffer. MIT license.
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const CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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const LOOKUP = new Uint8Array(256);
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for (let i = 0; i < CHARS.length; i++) {
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LOOKUP[CHARS.charCodeAt(i)] = i;
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}
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export function decodeBase64(base64) {
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let bufferLength = base64.length * 0.75;
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if (base64[base64.length - 1] === '=') {
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bufferLength--;
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if (base64[base64.length - 2] === '=') {
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bufferLength--;
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}
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}
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let bytes = new Uint8Array(bufferLength);
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let p = 0;
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for (let i = 0, len = base64.length; i < len; i += 4) {
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let encoded1 = LOOKUP[base64.charCodeAt(i)];
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let encoded2 = LOOKUP[base64.charCodeAt(i + 1)];
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let encoded3 = LOOKUP[base64.charCodeAt(i + 2)];
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let encoded4 = LOOKUP[base64.charCodeAt(i + 3)];
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bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
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bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
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bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
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}
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return bytes;
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}
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