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Problem solution · Go

Codeforces 359C — Prime Number

Codeforces 359C — Prime Number: 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
167 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 359C — Prime Number, 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

  • 167 lines of Go from the credited upstream file 359C.go.
  • The implementation visibly relies on sequence storage.
  • 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 359C — Prime Number · GoGo
Use this to learn the idea, then write your own version.
package main import (	"bufio"	. "fmt"	"io"	"time") // https://space.bilibili.com/206214type node59 struct {	lr       [2]*node59	priority uint	key      int64	value    int	subCnt   int} func (o *node59) size() int {	if o != nil {		return o.subCnt	}	return 0} func (o *node59) maintain() { o.subCnt = 1 + o.lr[0].size() + o.lr[1].size() } func (o *node59) rotate(d int) *node59 {	x := o.lr[d^1]	o.lr[d^1] = x.lr[d]	x.lr[d] = o	o.maintain()	x.maintain()	return x} type treap59 struct {	rd   uint	root *node59} func (t *treap59) fastRand() uint {	t.rd ^= t.rd << 13	t.rd ^= t.rd >> 17	t.rd ^= t.rd << 5	return t.rd} func (t *treap59) size() int { return t.root.size() } func (t *treap59) _put(o *node59, key int64, value int) *node59 {	if o == nil {		return &node59{priority: t.fastRand(), key: key, value: value, subCnt: 1}	}	if d := o.cmp(key); d >= 0 {		o.lr[d] = t._put(o.lr[d], key, value)		if o.lr[d].priority > o.priority {			o = o.rotate(d ^ 1)		}	} else {		o.value += value	}	o.maintain()	return o} func (t *treap59) put(key int64, value int) { t.root = t._put(t.root, key, value) } func (t *treap59) _delete(o *node59, key int64) *node59 {	if o == nil {		return nil	}	if d := o.cmp(key); d >= 0 {		o.lr[d] = t._delete(o.lr[d], key)	} else {		if o.lr[1] == nil {			return o.lr[0]		}		if o.lr[0] == nil {			return o.lr[1]		}		d = 0		if o.lr[0].priority > o.lr[1].priority {			d = 1		}		o = o.rotate(d)		o.lr[d] = t._delete(o.lr[d], key)	}	o.maintain()	return o} func (t *treap59) delete(key int64) { t.root = t._delete(t.root, key) } func (o *node59) cmp(a int64) int {	b := o.key	if a == b {		return -1	}	if a < b {		return 0	}	return 1} func (t *treap59) min() (min *node59) {	for o := t.root; o != nil; o = o.lr[0] {		min = o	}	return} func CF359C(_r io.Reader, out io.Writer) {	const mod = 1_000_000_007	pow := func(x, n int64) (res int64) {		x %= mod		res = 1		for ; n > 0; n /= 2 {			if n%2 > 0 {				res = res * x % mod			}			x = x * x % mod		}		return	}	min := func(a, b int64) int64 {		if a > b {			return b		}		return a	}	in := bufio.NewReader(_r)	var n, x int	s := int64(0)	Fscan(in, &n, &x)	a := make([]int64, n)	for i := range a {		Fscan(in, &a[i])		s += a[i]	} 	t := &treap59{rd: uint(time.Now().UnixNano())/2 + 1}	for _, v := range a {		t.put(s-v, 1)	} 	ans := int64(1)	for t.size() > 0 {		top := t.min()		k, e := top.value, top.key		if k%x > 0 {			ans = pow(int64(x), min(s, e))			break		}		e2 := int64(0)		for k%x == 0 {			k /= x			e2++		}		t.delete(e)		t.put(e+e2, k)	}	Fprint(out, ans)} //func main() { CF359C(os.Stdin, os.Stdout) }

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