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Problem solution · Go

Codeforces 527C — Glass Carving

Codeforces 527C — Glass Carving: a Go solution using direct simulation. Learn the idea, check the complexity, and read the full code, with credit to EndlessCheng Codeforces Go.

Technique
Direct simulation
Source
EndlessCheng Codeforces Go
Length
186 lines
Start with the idea.

Try the problem first. If you get stuck, read the approach below, then write your own solution. The full code is at the bottom.

Approach

Direct simulation

For Codeforces 527C — Glass Carving, the implementation follows the problem’s operations directly while maintaining only the state needed for the next decision.

  1. Translate each rule into one explicit state update.
  2. Maintain the invariant after every processed item.
  3. Return the accumulated state once all relevant input has been handled.

Code notes

  • 186 lines of Go from the credited upstream file 527C_treap.go.
  • The implementation keeps its working state in language-native values and containers.
  • No explicit loop blocks detected.

Complexity

Count the number and nesting of passes over the input, then include the maintained containers in the memory estimate.

Check the problem constraints before deciding whether this complexity will pass.

Source

Code and credit

This code comes from EndlessCheng Codeforces Go by Σndless (EndlessCheng) and is used under the MIT licence.

Open problem ↗Original source ↗
Full codeCodeforces 527C — Glass Carving · GoGo
Use this to learn the idea, then write your own version.
package main import (	"bufio"	. "fmt"	"io") var _x527C = uint(1) func fastRand527C() uint {	_x527C ^= _x527C << 13	_x527C ^= _x527C >> 17	_x527C ^= _x527C << 5	return _x527C} type node527C struct {	lr       [2]*node527C	priority uint	msz      int	key      int	value    int} func (o *node527C) pushUp() {	msz := o.value	if ol := o.lr[0]; ol != nil {		msz += ol.msz	}	if or := o.lr[1]; or != nil {		msz += or.msz	}	o.msz = msz} type treap527C struct {	root       *node527C	comparator func(a, b int) int} func newTreap527C() *treap527C {	return &treap527C{comparator: func(a, b int) int {		if a < b {			return 0		}		if a > b {			return 1		}		return -1	}}} func (t *treap527C) rotate(o *node527C, d int) *node527C {	x := o.lr[d^1]	o.lr[d^1] = x.lr[d]	x.lr[d] = o	x.msz = o.msz	o.pushUp()	return x} func (t *treap527C) _put(o *node527C, key int) *node527C {	if o == nil {		return &node527C{priority: fastRand527C(), msz: 1, key: key, value: 1}	}	if cmp := t.comparator(key, o.key); cmp >= 0 {		o.lr[cmp] = t._put(o.lr[cmp], key)		if o.lr[cmp].priority > o.priority {			o = t.rotate(o, cmp^1)		}	} else {		o.value++	}	o.pushUp()	return o} func (t *treap527C) put(key int) { t.root = t._put(t.root, key) } func (t *treap527C) _delete(o *node527C, key int) *node527C {	if o == nil {		return nil	}	if cmp := t.comparator(key, o.key); cmp >= 0 {		o.lr[cmp] = t._delete(o.lr[cmp], key)	} else {		if o.value > 1 {			o.value--		} else {			if o.lr[1] == nil {				return o.lr[0]			}			if o.lr[0] == nil {				return o.lr[1]			}			cmp2 := 0			if o.lr[0].priority > o.lr[1].priority {				cmp2 = 1			}			o = t.rotate(o, cmp2)			o.lr[cmp2] = t._delete(o.lr[cmp2], key)		}	}	o.pushUp()	return o} func (t *treap527C) delete(key int) { t.root = t._delete(t.root, key) } func (t *treap527C) floor(key int) (floor *node527C) {	for o := t.root; o != nil; {		switch cmp := t.comparator(key, o.key); {		case cmp == 0:			o = o.lr[0]		case cmp > 0:			floor = o			o = o.lr[1]		default:			return o		}	}	return} func (t *treap527C) next(key int) (next *node527C) {	for o := t.root; o != nil; {		if cmp := t.comparator(key, o.key); cmp != 0 {			o = o.lr[1]		} else {			next = o			o = o.lr[0]		}	}	return} func (t *treap527C) max() (max *node527C) {	for o := t.root; o != nil; o = o.lr[1] {		max = o	}	return} // github.com/EndlessCheng/codeforces-gofunc Sol527CTreap(reader io.Reader, writer io.Writer) {	cut := func(t, mt *treap527C, mid int) {		o := t.floor(mid)		l := o.key		r := t.next(l).key		mt.delete(r - l)		mt.put(r - mid)		mt.put(mid - l)		t.put(mid)	} 	in := bufio.NewReader(reader)	out := bufio.NewWriter(writer)	defer out.Flush() 	w, h, mw, mh := newTreap527C(), newTreap527C(), newTreap527C(), newTreap527C()	var w0, h0, n int	Fscan(in, &w0, &h0, &n)	w.put(0)	w.put(w0)	mw.put(w0)	h.put(0)	h.put(h0)	mh.put(h0)	for ; n > 0; n-- {		var op string		var mid int		Fscan(in, &op, &mid)		if op[0] == 'V' {			cut(w, mw, mid)		} else {			cut(h, mh, mid)		}		Fprintln(out, int64(mw.max().key)*int64(mh.max().key))	}} //func main() {//	Sol527CTreap(os.Stdin, os.Stdout)//}

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