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

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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 105using 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;}