139 lines
3.6 KiB
JavaScript
139 lines
3.6 KiB
JavaScript
const peq = new Uint32Array(0x10000);
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const myers_32 = (a, b) => {
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const n = a.length;
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const m = b.length;
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const lst = 1 << (n - 1);
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let pv = -1;
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let mv = 0;
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let sc = n;
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let i = n;
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while (i--) {
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peq[a.charCodeAt(i)] |= 1 << i;
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}
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for (i = 0; i < m; i++) {
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let eq = peq[b.charCodeAt(i)];
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const xv = eq | mv;
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eq |= ((eq & pv) + pv) ^ pv;
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mv |= ~(eq | pv);
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pv &= eq;
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if (mv & lst) {
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sc++;
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}
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if (pv & lst) {
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sc--;
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}
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mv = (mv << 1) | 1;
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pv = (pv << 1) | ~(xv | mv);
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mv &= xv;
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}
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i = n;
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while (i--) {
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peq[a.charCodeAt(i)] = 0;
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}
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return sc;
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};
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const myers_x = (b, a) => {
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const n = a.length;
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const m = b.length;
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const mhc = [];
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const phc = [];
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const hsize = Math.ceil(n / 32);
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const vsize = Math.ceil(m / 32);
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for (let i = 0; i < hsize; i++) {
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phc[i] = -1;
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mhc[i] = 0;
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}
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let j = 0;
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for (; j < vsize - 1; j++) {
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let mv = 0;
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let pv = -1;
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const start = j * 32;
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const vlen = Math.min(32, m) + start;
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for (let k = start; k < vlen; k++) {
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peq[b.charCodeAt(k)] |= 1 << k;
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}
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for (let i = 0; i < n; i++) {
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const eq = peq[a.charCodeAt(i)];
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const pb = (phc[(i / 32) | 0] >>> i) & 1;
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const mb = (mhc[(i / 32) | 0] >>> i) & 1;
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const xv = eq | mv;
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const xh = ((((eq | mb) & pv) + pv) ^ pv) | eq | mb;
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let ph = mv | ~(xh | pv);
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let mh = pv & xh;
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if ((ph >>> 31) ^ pb) {
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phc[(i / 32) | 0] ^= 1 << i;
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}
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if ((mh >>> 31) ^ mb) {
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mhc[(i / 32) | 0] ^= 1 << i;
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}
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ph = (ph << 1) | pb;
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mh = (mh << 1) | mb;
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pv = mh | ~(xv | ph);
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mv = ph & xv;
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}
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for (let k = start; k < vlen; k++) {
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peq[b.charCodeAt(k)] = 0;
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}
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}
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let mv = 0;
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let pv = -1;
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const start = j * 32;
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const vlen = Math.min(32, m - start) + start;
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for (let k = start; k < vlen; k++) {
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peq[b.charCodeAt(k)] |= 1 << k;
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}
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let score = m;
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for (let i = 0; i < n; i++) {
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const eq = peq[a.charCodeAt(i)];
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const pb = (phc[(i / 32) | 0] >>> i) & 1;
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const mb = (mhc[(i / 32) | 0] >>> i) & 1;
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const xv = eq | mv;
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const xh = ((((eq | mb) & pv) + pv) ^ pv) | eq | mb;
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let ph = mv | ~(xh | pv);
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let mh = pv & xh;
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score += (ph >>> (m - 1)) & 1;
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score -= (mh >>> (m - 1)) & 1;
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if ((ph >>> 31) ^ pb) {
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phc[(i / 32) | 0] ^= 1 << i;
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}
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if ((mh >>> 31) ^ mb) {
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mhc[(i / 32) | 0] ^= 1 << i;
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}
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ph = (ph << 1) | pb;
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mh = (mh << 1) | mb;
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pv = mh | ~(xv | ph);
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mv = ph & xv;
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}
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for (let k = start; k < vlen; k++) {
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peq[b.charCodeAt(k)] = 0;
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}
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return score;
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};
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const distance = (a, b) => {
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if (a.length < b.length) {
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const tmp = b;
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b = a;
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a = tmp;
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}
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if (b.length === 0) {
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return a.length;
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}
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if (a.length <= 32) {
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return myers_32(a, b);
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}
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return myers_x(a, b);
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};
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const closest = (str, arr) => {
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let min_distance = Infinity;
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let min_index = 0;
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for (let i = 0; i < arr.length; i++) {
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const dist = distance(str, arr[i]);
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if (dist < min_distance) {
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min_distance = dist;
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min_index = i;
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}
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}
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return arr[min_index];
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};
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export { closest, distance };
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