119 lines
3.9 KiB
TypeScript
119 lines
3.9 KiB
TypeScript
module es {
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/**
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* 这个类可以从两方面来考虑。你可以把它看成一个位向量或者一组非负整数。这个名字有点误导人。
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*
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* 它是由一个位向量实现的，但同样可以把它看成是一个非负整数的集合;集合中的每个整数由对应索引处的集合位表示。该结构的大小由集合中的最大整数决定。
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*/
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export class BitSet {
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private static ADDRESS_BITS_PER_WORD = 5;
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private static BITS_PER_WORD = 1 << BitSet.ADDRESS_BITS_PER_WORD; // 32
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private static WORD_MASK : number = 0xffffffff;
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private words_: number[];
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constructor(nbits: number = 0) {
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this.words_ = [];
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}
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public clear(bitIndex?: number) {
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if (bitIndex === null) {
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const words = this.words_;
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let wordsInUse = words.length;
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while (wordsInUse > 0) {
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words[--wordsInUse] = 0;
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}
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return;
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}
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const wordIndex = bitIndex >> BitSet.ADDRESS_BITS_PER_WORD;
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this.words_[wordIndex] &= ~(1 << bitIndex);
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}
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public get(bitIndex: number): boolean {
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const wordIndex = bitIndex >> BitSet.ADDRESS_BITS_PER_WORD;
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const words = this.words_;
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const wordsInUse = words.length;
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return wordIndex < wordsInUse && (words[wordIndex] & (1 << bitIndex)) != 0;
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}
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public intersects(set: BitSet) {
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const words = this.words_;
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const wordsInUse = words.length;
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for (let i = Math.min(wordsInUse, set.words_.length) - 1; i >= 0; i--)
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if ((words[i] & set.words_[i]) != 0) return true;
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return false;
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}
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public isEmpty(): boolean {
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return this.words_.length === 0;
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}
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public nextSetBit(fromIndex: number) {
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let u = fromIndex >> BitSet.ADDRESS_BITS_PER_WORD;
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const words = this.words_;
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const wordsInUse = words.length;
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let word = words[u] & (BitSet.WORD_MASK << fromIndex);
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while (true) {
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if (word !== 0) return u * BitSet.BITS_PER_WORD + this.numberOfTrailingZeros(word);
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if (++u === wordsInUse) return -1;
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word = words[u];
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}
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}
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private numberOfTrailingZeros(i: number): number {
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if (i == 0) return 64;
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let x: number = i;
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let y: number;
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let n = 63;
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y = x << 32;
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if (y != 0) {
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n -= 32;
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x = y;
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}
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y = x << 16;
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if (y != 0) {
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n -= 16;
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x = y;
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}
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y = x << 8;
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if (y != 0) {
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n -= 8;
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x = y;
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}
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y = x << 4;
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if (y != 0) {
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n -= 4;
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x = y;
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}
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y = x << 2;
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if (y != 0) {
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n -= 2;
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x = y;
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}
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return n - ((x << 1) >>> 63);
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}
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public set(bitIndex: number, value: boolean = true) {
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const wordIndex = bitIndex >> BitSet.ADDRESS_BITS_PER_WORD;
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const words = this.words_;
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const wordsInUse = words.length;
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const wordsRequired = wordIndex + 1;
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if (wordsInUse < wordsRequired) {
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words.length = Math.max(2 * wordsInUse, wordsRequired);
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for (let i = wordsInUse, l = words.length; i < l; i++) {
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words[i] = 0;
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}
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}
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if (value) {
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return (words[wordIndex] |= 1 << bitIndex);
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} else {
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return (words[wordIndex] &= ~(1 << bitIndex));
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}
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}
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}
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}
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