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Problem solution · Go

Codeforces 1111C — Creative Snap

Codeforces 1111C — Creative Snap: 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
52 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 1111C — Creative Snap, 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

  • 52 lines of Go from the credited upstream file 1111C.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 1111C — Creative Snap · GoGo
Use this to learn the idea, then write your own version.
package main import (	"bufio"	. "fmt"	"io"	"sort") // github.com/EndlessCheng/codeforces-gofunc Sol1111C(reader io.Reader, writer io.Writer) {	in := bufio.NewReader(reader)	out := bufio.NewWriter(writer)	defer out.Flush() 	var n, k int	var a, b int64	Fscan(in, &n, &k, &a, &b)	arr := make([]int, k)	for i := range arr {		Fscan(in, &arr[i])	}	sort.Ints(arr) 	var f func(l, r int) int64	f = func(l, r int) int64 {		// 改成手写二分能快一倍！		// 非手写二分 514ms https://codeforces.com/contest/1111/submission/62602788		// 　手写二分 249ms https://codeforces.com/contest/1111/submission/62603480		li := sort.Search(k, func(i int) bool { return arr[i] >= l })		ri := sort.Search(k, func(i int) bool { return arr[i] >= r+1 })		// 也可以写成下面这样，可能会快一点点(<10%)		//ri := sort.Search(k-li, func(i int) bool { return arr[i+li] >= r+1 }) + li		if li == ri {			return a		}		ans := b * int64(ri-li) * int64(r-l+1)		if l < r {			mid := (l + r) >> 1			if newAns := f(l, mid) + f(mid+1, r); newAns < ans {				ans = newAns			}		}		return ans	}	Fprint(out, f(1, 1<<uint(n)))} //func main() {//	Sol1111C(os.Stdin, os.Stdout)//}

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