Imported Upstream version 1.4upstream/1.4

1 files changed, 47 insertions, 0 deletions

diff --git a/src/container/heap/example_intheap_test.go b/src/container/heap/example_intheap_test.go
new file mode 100644
index 000000000..02d3d8668
--- /dev/null
+++ b/src/container/heap/example_intheap_test.go
@@ -0,0 +1,47 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This example demonstrates an integer heap built using the heap interface.
+package heap_test
+
+import (
+	"container/heap"
+	"fmt"
+)
+
+// An IntHeap is a min-heap of ints.
+type IntHeap []int
+
+func (h IntHeap) Len() int           { return len(h) }
+func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] }
+func (h IntHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+
+func (h *IntHeap) Push(x interface{}) {
+	// Push and Pop use pointer receivers because they modify the slice's length,
+	// not just its contents.
+	*h = append(*h, x.(int))
+}
+
+func (h *IntHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+// This example inserts several ints into an IntHeap, checks the minimum,
+// and removes them in order of priority.
+func Example_intHeap() {
+	h := &IntHeap{2, 1, 5}
+	heap.Init(h)
+	heap.Push(h, 3)
+	fmt.Printf("minimum: %d\n", (*h)[0])
+	for h.Len() > 0 {
+		fmt.Printf("%d ", heap.Pop(h))
+	}
+	// Output:
+	// minimum: 1
+	// 1 2 3 5
+}