ZZUOJ-10434: good string

Description

给定一个字符串，判断它是否是good string。
good string定义为：
① 字符s是good string，字符p是good string，字符y也是good string
② P和Q都是good string，则PQ是good string
③ P是good string，则(P)是good string
④ P是good string，则!P是good string
⑤ P和Q都是good string，则P|Q和P&Q是good string

Input

输入包含多组数据。每组数据为一行一个字符串，长度不超过100。

Output

对于每组数据，如果P是good string则输出”P is a good string”，否则输出”P is not a good string”。

Sample Input

!spy
!(s|p!y)
)sp|y

Sample Output

!spy is a good string
!(s|p!y) is a good string
)sp|y is not a good string

郑州大学第九届ACM大学生程序设计竞赛题目。

/* * 分类：区间DP * dp[i][j]表示i到j之间的那个字符串是否为good string * 我们所求答案即为dp[1][len] * dp转移方程见下列代码 * * Name: 10434: good string * Copyright: __X * Author: long_long_ago * Date: 18/12/15 08:25 * Description: http://acm.zzu.edu.cn:8000/problem.php?id=10434 * */

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>
#define N 105

using namespace std;
int dp[N][N];
char str[N];
int main()
{
#ifndef ONLINE_JUDGE
    freopen("1.txt", "r", stdin);
#endif
    int i, j, k, l, len, s, e;
    bool flag;
    while(~scanf("%s", str+1))
    {
        flag = false;
        len = strlen(str+1);
        for (i = 1; i <= len; i++)
        {
            if (str[i] == 's' || str[i] == 'p' || str[i] == 'y' || str[i] == '|' || str[i] == '&'
                || str[i] == '(' || str[i] == ')' || str[i] == '!')
            {
                continue;
            }
            else
            {
                cout << str+1 << " is not a good string" << endl;
                flag = true;
                break;
            }
        }
        if (flag)   continue;
        memset(dp, 0, sizeof(dp));
        for (i = 1; i <= len; i++)
        {
            if (str[i] == 's' || str[i] == 'p' || str[i] == 'y')    dp[i][i] = 1;
        }
        for (l = 2; l <= len; l++)
        {
            for (s = 1; s <= len - l + 1; s++)
            {
                e = s + l - 1;
                if (e-s >= 2 && str[s] == '(' && str[e] == ')' && dp[s+1][e-1])
                {
                    dp[s][e] = 1;
                    continue;
                }
                if (str[s] == '!' && dp[s+1][e])
                {
                    dp[s][e] = 1;
                    continue;
                }
                for(j = s + 1; j < e; j++)
                {
                    if (dp[s][j-1] && dp[j+1][e])
                    {
                        if (str[j] == '|' || str[j] == '&')
                        {
                            dp[s][e] = 1;
                            break;
                        }
                    }
                }
                for(k = s; k < e; k++)
                {
                    if (dp[s][k] &&dp[k+1][e])
                    {
                        dp[s][e] = 1;
                        break;
                    }
                } 
            }
        }
        if(dp[1][len])
            printf("%s is a good string\n", str + 1);
        else printf("%s is not a good string\n", str + 1);
    }
    return 0;
}

下面是某大神的写法 (╯▽╰)

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <stack>
using namespace std;
typedef long long LL;
const int N = 5e2 + 17;
char s[N];

char f[] = "spy!|&()";
int sc(char x)
{
    for(int i = 0; i < 8; i ++)
        if(x == f[i])
            return 1;
    return 0;
}

int check()
{
    stack<char> kh;
    while(!kh.empty())kh.pop();
    for(int i = 0; s[i]; i ++)
    {
        if(!sc(s[i]))
            return 0;
        if(s[i] == '(')
            kh.push('(');
        else if(s[i] == ')')
        {
            if(kh.empty())
                return 0;
            else
                kh.pop();
            if(s[i-1] == '|' || s[i-1] == '&' || s[i-1] == '(' || s[i-1] == '!')
                return 0;
        }
        else if(s[i] == '|' || s[i] == '&')
            if(i < 1 || s[i-1] == '|' || s[i-1] == '&' || s[i-1] == '!' || s[i-1] == '(')
                return 0;
    }

    int len = strlen(s);
    if(s[len-1] == '|' || s[len-1] == '&' || s[len-1] == '!')
        return 0;

    return kh.empty();
}

int main()
{
    while(gets(s))
        printf("%s %s\n", s, check() ? "is a good string" : "is not a good string");
    return 0;
}