Golang 实现Bit数组

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《The Go Programming Language》 笔记

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import (    "bytes"    "fmt")const target int = 32 << (^uint(0) >> 63) //判断当前系统是32位还是64位type IntSet struct {    words []uint}func (s *IntSet) Has(x int) bool {    word, bit := x/target, uint(x%target)    return word < len(s.words) && s.words[word]&(1<<bit) != 0}func (s *IntSet) Add(numbers ...int) {    for _, numebr := range numbers {        x := numebr        word, bit := x/target, uint(x%target)        for word >= len(s.words) {            s.words = append(s.words, 0)        }        s.words[word] |= 1 << bit    }}func (s *IntSet) String() string {    var buf bytes.Buffer    buf.WriteByte('{')    for i, word := range s.words {        if word == 0 {            continue        }        for j := 0; j < 64; j++ {            if word&(1<<uint(j)) != 0 {                if buf.Len() > len("{") {                    buf.WriteByte(' ')                }                fmt.Fprintf(&buf, "%d", 64*i+j)            }        }    }    buf.WriteByte('}')    return buf.String()}//并集，合并s,tfunc UnionWith(s, t *IntSet) *IntSet {    uw := &IntSet{}    slen, tlen := len(s.words), len(t.words)    minlen := slen    if minlen > tlen {        minlen = tlen    }    for i := 0; i < minlen; i++ {        uw.words = append(uw.words, s.words[i]|t.words[i])    }    if minlen == tlen {        union(uw, s, minlen, slen)    } else {        union(uw, t, minlen, tlen)    }    return uw}//交集,元素在s,t中均出现func InersectWith(s, t *IntSet) *IntSet {    iw := &IntSet{}    slen, tlen := len(s.words), len(t.words)    minlen := slen    if minlen > tlen {        minlen = tlen    }    for i := 0; i < minlen; i++ {        iw.words = append(iw.words, s.words[i]&t.words[i])    }    if minlen == tlen { //s元素更多, 多余的元素全部置为0        for minlen < slen {            iw.words = append(iw.words, s.words[minlen]&0)            minlen++        }    }    return iw}//差集，元素出现在s，未出现在tfunc DifferenceWith(s, t *IntSet) *IntSet {    dw := &IntSet{}    slen, tlen := len(s.words), len(t.words)    minlen := slen    if minlen > tlen {        minlen = tlen    }    for i := 0; i < minlen; i++ {        mask := s.words[i] & t.words[i]        dw.words = append(dw.words, s.words[i]^mask)    }    if minlen == tlen && minlen < slen {        union(dw, s, minlen, slen)    }    return dw}//并差集，元素出现在s但未出现在t，或者元素出现在t但未出现在sfunc SymmetricDifference(s, t *IntSet) *IntSet {    sd := &IntSet{}    slen, tlen := len(s.words), len(t.words)    minlen := slen    if minlen > tlen {        minlen = tlen    }    for i := 0; i < minlen; i++ {        sd.words = append(sd.words, s.words[i]^t.words[i])    }    if minlen == tlen {        union(sd, s, minlen, slen)    } else {        union(sd, t, minlen, tlen)    }    return sd}//从tmplen开始，将is中的元素复制到resfunc union(res, is *IntSet, tmplen, xlen int) {    for tmplen < xlen {        res.words = append(res.words, is.words[tmplen])        tmplen++    }}func main() {    var x, y IntSet    x.Add(0)    x.Add(1, 3, 5, 7)    x.Add(9)    x.Add(63)    x.Add(100)    fmt.Println("x : ", x.String())    y.Add(9)    y.Add(42)    y.Add(7)    y.Add(5)    fmt.Println("y : ", y.String())    result1 := UnionWith(&x, &y)    fmt.Println("x UnionWith y : ", result1.String())    result2 := InersectWith(&x, &y)    fmt.Println("x InersectWith y : ", result2.String())    result3 := DifferenceWith(&x, &y)    fmt.Println("x DifferenceWith y : ", result3.String())    result4 := SymmetricDifference(&x, &y)    fmt.Println("x SymmetricDifference y : ", result4.String())}