Golang Interface.Less方法代码示例

// Simple insertion sort for smaller data collections.
func insertionSort(data sort.Interface, lo, hi int) {
	for i := lo + 1; i < hi+1; i++ {
		for j := i; j > lo && data.Less(j, j-1); j-- {
			data.Swap(j, j-1)
		}
	}
}

// Partial quicksort algorithm due to Martínez (2004),
// http://www.cs.upc.edu/~conrado/research/reports/ALCOMFT-TR-03-50.pdf
func partialSort(data sort.Interface, k, lo, hi int) {
	for hi-lo > 5 {
		p := medianOfThree(data, lo, hi)
		p = partition(data, lo, hi, p)
		if p < k-1 {
			partialSort(data, k, p+1, hi)
		}
		hi = p
	}

	// Finish off with a selection sort.
	if hi-lo-1 < k {
		k = hi - lo - 1
	}
	for ; k > 0; k-- {
		min := lo
		for i := lo + 1; i < hi; i++ {
			if data.Less(i, min) {
				min = i
			}
		}
		data.Swap(lo, min)
		lo++
	}
}

// InsertionSort 插入排序，时间复杂度O(n^2)。
//
// 这个实现是拷贝的sort包下的 insertionSort()。
func InsertionSort(data sort.Interface, start, end int) {
	for i := start + 1; i < end; i++ {
		for j := i; j > start && data.Less(j, j-1); j-- {
			data.Swap(j, j-1)
		}
	}
}

// HeapSort sorts given data and has next properties:
//
// - Not stable
// - O(1) extra space
// - O(n*lg(n)) time
// - Not really adaptive
//
func HeapSort(data sort.Interface) {
	// down restores order of heap.
	down := func(root, n int) {
		for {
			lch := 2*root + 1
			if lch >= n || lch < 0 { // child < 0 when int overflow.
				break
			}
			if rch := lch + 1; rch < n && data.Less(lch, rch) { // lch+1 == 2*root + 2 // Right child.
				lch = rch
			}
			if !data.Less(root, lch) { // Heap is ordered.
				return
			}
			data.Swap(root, lch)
			root = lch
		}
	}

	// Heapify (build a max heap).
	for i := (data.Len() - 1) / 2; i >= 0; i-- {
		down(i, data.Len())
	}

	// Pop elements, largest first, into end of data.
	// Loop invariant: data[i:] contains the data.Len()-1-i largest elements
	// of maxHeap and the maxHeap contains i+1 smallest elements.
	for i := data.Len() - 1; i >= 0; i-- {
		data.Swap(0, i)
		down(0, i)
	}
}

func isort(A sort.Interface, a, b int) {
	for j := a + 1; j < b; j++ {
		for i := j; i > a && A.Less(i, i-1); i-- {
			A.Swap(i, i-1)
		}
	}
}

// partition the subarray a[lo .. hi] by returning an index j
// so that a[lo .. j-1] <= a[j] <= a[j+1 .. hi]
func partition(a sort.Interface, lo, hi int) int {
	i, j := lo+1, hi
	// v = a[lo]
	for {
		for a.Less(i, lo) {
			if i == hi {
				break
			}
			i++
		}
		for a.Less(lo, j) {
			if j == lo {
				break
			}
			j--
		}
		if i >= j {
			break
		}
		a.Swap(i, j)
		i++
		j--
	}
	// put v = a[j] into position
	a.Swap(lo, j)
	// with a[lo .. j-1] <= a[j] <= a[j+1 .. hi]
	return j
}

// Insert adds in-order element of sort.Interface at index Tree.Len()
// It doesn't check for equality, so duplicates are inserted in
// stable order.
func (t *Tree) Insert(data sort.Interface) {
	ix := len(t.nodes)
	if ix == MaxSize {
		panic("tree size exceed maximum")
	}
	t.nodes = append(t.nodes, node{null, null, null, 1})
	if ix == 0 {
		t.root, t.min, t.max = 0, 0, 0
		return
	}
	var dir direction
	cur := t.root
	curnode := &t.nodes[cur]
	for {
		dir = direction(!data.Less(ix, int(cur)))

		if curnode.link(dir) == null {
			break
		}
		cur = curnode.link(dir)
		curnode = &t.nodes[cur]
	}
	node := &t.nodes[ix]
	node._parent = index(cur)
	curnode.set_link(dir, ix)
	if dir == right {
		if cur == t.max {
			t.max = ix
		}
	} else if cur == t.min {
		t.min = ix
	}
	t.balance(cur)
}

func check(t *testing.T, data sort.Interface, tree *Tree, ix int) int8 {
	node := &tree.nodes[ix]
	l, r := int(node._left), int(node._right)
	var lh, rh int8
	if l != null {
		if data.Less(ix, l) {
			t.Fatalf("%d < %d", ix, l)
		}
		lh = check(t, data, tree, l)
	} else {
		lh = 0
	}
	if r != null {
		if data.Less(r, ix) {
			t.Fatalf("%d < %d", r, ix)
		}
		rh = check(t, data, tree, r)
	} else {
		rh = 0
	}
	bal := lh - rh
	if bal < -1 || bal > 1 || tree.bal(ix) != bal {
		t.Fatalf("height fails: %d [%d, %d]",
			ix, lh, rh)
	}
	return max_i8(lh, rh) + 1
}

// TimSort sorts the data defined by sort.Interface.
func TimSort(a sort.Interface) (err error) {
	indexes := make([]int, a.Len())
	for i := 0; i < len(indexes); i++ {
		indexes[i] = i
	} // for i

	err = Ints(indexes, func(i, j int) bool {
		return a.Less(i, j)
	})

	if err != nil {
		return err
	} // if

	for i := 0; i < len(indexes); i++ {
		j := indexes[i]
		if j == 0 {
			continue
		} //  if
		for k := i; j != i; {
			a.Swap(j, k)
			k, j, indexes[j] = j, indexes[j], 0
		} // for j
	} // for i

	return nil
}

func insertionSort(a sort.Interface) {
	for i := 1; i < a.Len(); i++ {
		for j := i; j > 0 && a.Less(j, j-1); j-- {
			a.Swap(j-1, j)
		}
	}
}

// Insertion sort
func insertionSort(data sort.Interface, a, b int) {
	for i := a + 1; i < b; i++ {
		for j := i; j > a && data.Less(j, j-1); j-- {
			data.Swap(j, j-1)
		}
	}
}

func Quicksort(sortable sort.Interface) {

	partition := func(sortable sort.Interface, lo, hi int) int {
		pivot := hi
		i := lo
		for j := lo; j < hi; j++ {
			if sortable.Less(j, pivot) {
				sortable.Swap(i, j)
				i++
			}
		}
		sortable.Swap(i, hi)
		return i
	}

	var quicksortRecursive func(sortable sort.Interface, lo, hi int)

	quicksortRecursive = func(sortable sort.Interface, lo, hi int) {
		if lo < hi {
			p := partition(sortable, lo, hi)
			quicksortRecursive(sortable, lo, p-1)
			quicksortRecursive(sortable, p+1, hi)
		}
	}

	quicksortRecursive(sortable, 0, sortable.Len()-1)

}

// Make a random comparison with certain probability of correctness
func randLess(i, j int, cmp sort.Interface, pCorrect float64) bool {
	if rand.Float64() <= pCorrect {
		return cmp.Less(i, j)
	} else {
		return !cmp.Less(i, j)
	}
}

// InsertionSort performs a simple insertion sort on the sort interface. In the
// case of ByDist it performs generally as fast as sort.Sort() except that it
// can exploit temporal coherence improving performance dramatically when the
// objects have not moved much.
func InsertionSort(data sort.Interface) {
	for i := 0; i < data.Len(); i++ {
		for j := i; j > 0 && data.Less(j, j-1); j-- {
			data.Swap(j, j-1)
		}
	}
}

// Insertion sort
func Insertion(a sort.Interface) {
	for i := 2; i < a.Len(); i++ {
		// insert a[j] into sorted slice a[0:j]
		for j := i; j > 0 && a.Less(j, j-1); j-- {
			a.Swap(j, j-1)
		}
	}
}