<style>

html, body, .ui-content {
background-color: #333;
color: #ddd;
}

body > .ui-infobar {
display: none;
}

.ui-view-area > .ui-infobar {
display: block;
}

.markdown-body h1{
color: #9CCEF2;
}
.markdown-body h2,
.markdown-body h3{
color: #B1D6CA;
}
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
color: #ddd;
}

.markdown-body h1,
.markdown-body h2 {
border-bottom-color: #ffffff69;
}

.markdown-body h1 .octicon-link,
.markdown-body h2 .octicon-link,
.markdown-body h3 .octicon-link,
.markdown-body h4 .octicon-link,
.markdown-body h5 .octicon-link,
.markdown-body h6 .octicon-link {
color: #fff;
}

.markdown-body img {
background-color: transparent;
}

.ui-toc-dropdown .nav>.active:focus>a, .ui-toc-dropdown .nav>.active:hover>a, .ui-toc-dropdown .nav>.active>a {
color: white;
border-left: 2px solid white;
}

.expand-toggle:hover,
.expand-toggle:focus,
.back-to-top:hover,
.back-to-top:focus,
.go-to-bottom:hover,
.go-to-bottom:focus {
color: white;
}

.ui-toc-dropdown {
background-color: #333;
}

.ui-toc-label.btn {
background-color: #191919;
color: white;
}

.ui-toc-dropdown .nav>li>a:focus,
.ui-toc-dropdown .nav>li>a:hover {
color: white;
border-left: 1px solid white;
}

.markdown-body blockquote {
color: #bcbcbc;
}

.markdown-body table tr {
background-color: #5f5f5f;
}

.markdown-body table tr:nth-child(2n) {
background-color: #4f4f4f;
}

.markdown-body code,
.markdown-body tt {
color: #eee;
background-color: rgba(230, 230, 230, 0.36);
}

a,
.open-files-container li.selected a {
color: #5EB7E0;
}

</style>

###### tags: `tgirc早修book`

# Ch.06 題目練習

<font color="FEA0A0">**題目**</font>
1. [Zerojudge a442: Necklace Problem (NP)](https://zerojudge.tw/ShowProblem?problemid=a442)
2. [Toj 92 / 天線寶寶說你好](https://toj.tfcis.org/oj/pro/92/)
3. [Zerojudge d535: 2. 密碼驗證與擷取](https://zerojudge.tw/ShowProblem?problemid=d535)
4. [Zerojudge a038: 數字翻轉](https://zerojudge.tw/ShowProblem?problemid=a038)
5. [Zerojudge e267: 11192 - Group Reverse](https://zerojudge.tw/ShowProblem?problemid=e267)
6. [Kattis Quick Estimates](https://open.kattis.com/problems/quickestimate)
7. [Toj Reversed card open!](https://toj.tfcis.org/oj/pro/115/)
8. [Kattis Line Them Up](https://open.kattis.com/problems/lineup)
9. [Toj Hello world!](https://toj.tfcis.org/oj/pro/5/)
10. [Kattis Ragged Right](https://open.kattis.com/problems/raggedright)
11. [Toj J. Julius Caesar](https://toj.tfcis.org/oj/pro/127/)
12. [Toj 跳躍](https://toj.tfcis.org/oj/pro/113/)
13. [Kattis The Key to Cryptography](https://open.kattis.com/problems/keytocrypto)
14. [UVA Q11577 Letter Frequency](http://domen111.github.io/UVa-Easy-Viewer/?11577)
15. [Kattis Trik](https://open.kattis.com/problems/trik)
16. [Toj 4. Hello, TFcis!](https://toj.tfcis.org/oj/pro/294/)
17. [Zerojudge a011: 00494 - Kindergarten Counting Game](https://zerojudge.tw/ShowProblem?problemid=a011)

:::spoiler <font color="FEA0A0">**題解**</font>
>
1. [Zerojudge a442: Necklace Problem (NP)](https://zerojudge.tw/ShowProblem?problemid=a442)

#include <bits/stdc++.h>
using namespace std;

int main(){
    string str1, str2;
    while(cin >> str1 >> str2){
        int count = 0;
        str2 += str2;
        
        if( str2.find(str1, 0) != string::npos ) count++;
        
        reverse( str1.begin(), str1.end() );
        if( str2.find(str1, 0) != string::npos ) count++;

        if( count != 0)  cout << "same\n";
        else             cout << "difference\n";
      }
  
    return 0;
}

3. [Zerojudge d535: 2. 密碼驗證與擷取](https://zerojudge.tw/ShowProblem?problemid=d535)
函數解：

#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

int main(){
	string s;
	cin >> s;
	string ss = s;
	reverse(s.begin(), s.end()); //翻轉字串，以確認是否為迴文
    
	if(ss == s){
		string ans = "";
		int a, b;
		bool add = false;
        
		for(int i=1; i<ss.size(); i++){
			a = ss[i-1] - '0';
			b = ss[i] - '0';
			if(b > a*2){
				cout << "INCORRECT\n";
				return 0;
			}
			if(a%2 == 0){
				ans += ss[i - 1];
				add = true;
			}
		}
        
		if(b%2 == 0){
			ans += char(b + '0');
		}
		else if(!add) cout << "0";
		cout << ans << '\n';
	}
	else cout << "INCORRECT\n"; 
    
	return 0;
} 

非函數解

#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

int main(){
	string s;
	cin >> s;
    
	int len = s.size();
	for(int i=0; i<len/2; i++){
		if(s[i] != s[len-i-1]){
			cout << "INCORRECT\n";
			return 0;
		}
	}
    
	string ans="";
	for(int i=0; i<len-1; i++){
		if( s[i+1] - s[i] > s[i] - '0' ){
			cout << "INCORRECT\n";
			return 0;
		}
		if( int( s[i] - '0' )%2 == 0 ) ans += s[i];
	} 
    
	if( int( s[len-1] - '0')%2 == 0) ans += s[len-1];
    
	if(ans.size() == 0) cout << '0';
    
	cout << ans << '\n';
    
	return 0;
} 

4. [Zerojudge a038: 數字翻轉](https://zerojudge.tw/ShowProblem?problemid=a038)

#include<bits/stdc++.h>
using namespace std;

int main(){
	string str;
	cin >> str;
	reverse( str.begin(), str.end() );
	cout << stoi(str);
	
	return 0;
}

5. [Zerojudge e267: 11192 - Group Reverse](https://zerojudge.tw/ShowProblem?problemid=e267)

#include<bits/stdc++.h>
using namespace std;

int main(){
	string str;
	int G, n;
	
	while( cin >> G && G!=0){
		cin >> str;
		n = str.size() / G;
		for(int i=0; i<G; i++){
			reverse( str.begin() + i*n, str.begin() + (i+1)*n );
		}
		cout << str << '\n';
	}
	
	return 0;
}

:::