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Problem solution · Go

Codeforces 163E — e-Government

Codeforces 163E — e-Government: 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
148 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 163E — e-Government, 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

  • 148 lines of Go from the credited upstream file 163E.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 163E — e-Government · GoGo
Use this to learn the idea, then write your own version.
package main import (	"bufio"	. "fmt"	"io"	"strconv") // https://space.bilibili.com/206214type acamNode63 struct {	son  [26]uint32	fail uint32} var acamNodes63 [1e6 + 1]acamNode63 type acam63 struct {	root    uint32	nodeCnt uint32	g       [][]uint32} func (t *acam63) put(s string) uint32 {	o := t.root	for _, b := range s {		b -= 'a'		if acamNodes63[o].son[b] == 0 {			acamNodes63[o].son[b] = t.nodeCnt			t.nodeCnt++		}		o = acamNodes63[o].son[b]	}	return o} func (t *acam63) buildFail() {	t.g = make([][]uint32, t.nodeCnt)	q := make([]uint32, 0, t.nodeCnt)	for _, son := range acamNodes63[t.root].son[:] {		if son != 0 {			t.g[acamNodes63[son].fail] = append(t.g[acamNodes63[son].fail], son)			q = append(q, son)		}	}	for len(q) > 0 {		o := q[0]		q = q[1:]		f := acamNodes63[o].fail		for i, son := range acamNodes63[o].son[:] {			if son == 0 {				acamNodes63[o].son[i] = acamNodes63[f].son[i]				continue			}			acamNodes63[son].fail = acamNodes63[f].son[i]			t.g[acamNodes63[son].fail] = append(t.g[acamNodes63[son].fail], son)			q = append(q, son)		}	}} type fenwick63 []int32 func (f fenwick63) update(i, j uint32, val int32) {	for ; i < uint32(len(f)); i += i & -i {		f[i] += val	}	for ; j < uint32(len(f)); j += j & -j {		f[j] -= val	}} func (f fenwick63) pre(i uint32) (res int) {	for ; i > 0; i &= i - 1 {		res += int(f[i])	}	return} func CF163E(_r io.Reader, _w io.Writer) {	in := bufio.NewReader(_r)	out := bufio.NewWriter(_w)	defer out.Flush() 	var q, n int	var s string	Fscan(in, &q, &n)	t := &acam63{nodeCnt: 1}	nodeIDs := make([]uint32, n+1)	for i := 1; i <= n; i++ {		Fscan(in, &s)		nodeIDs[i] = t.put(s)	}	t.buildFail() 	g := t.g	nodes := make([]struct{ l, r uint32 }, len(g))	type pair struct{ v, i uint32 } 	// 手写递归栈，递归转循环，不然消耗 > 100MB 内存 MLE	st := []pair{{t.root, 0}}	nodes[t.root].l = 1	dfn := uint32(1)	for len(st) > 0 {		p := st[len(st)-1]		v, i := p.v, p.i		if i < uint32(len(g[v])) {			dfn++			w := g[v][i]			nodes[w].l = dfn			st[len(st)-1].i++			st = append(st, pair{w, 0})		} else {			nodes[v].r = dfn + 1			st = st[:len(st)-1]		}	} 	bit := make(fenwick63, dfn+2)	for i := 1; i <= n; i++ {		p := nodes[nodeIDs[i]]		bit.update(p.l, p.r, 1)	}	del := make([]bool, n+1)	for ; q > 0; q-- {		Fscan(in, &s)		if s[0] == '?' {			o := t.root			ans := 0			for _, b := range s[1:] {				o = acamNodes63[o].son[b-'a']				ans += bit.pre(nodes[o].l)			}			Fprintln(out, ans)		} else {			i, _ := strconv.Atoi(s[1:])			if del[i] == (s[0] == '-') {				continue			}			del[i] = !del[i]			p := nodes[nodeIDs[i]]			bit.update(p.l, p.r, int32(s[0]&3)-2)		}	}} //func main() { CF163E(os.Stdin, os.Stdout) }

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