POJ 1686

题意：给出两个含未知数的表达式，判断其是否相等。

题解：任意给未知数赋值，看起结果是否相同。

View Code

  1 #include<cstdio>

  2 #include<cstring>

  3 #include<algorithm>

  4 #include<cctype>

  5 using namespace std;

  6 const int N=1000;

  7 char op[8]= {'+','-','*','/','(',')','\0'};

  8 char cp[7][7]=

  9 {

 10     {'>','>','<','<','<','>','>'},

 11     {'>','>','<','<','<','>','>'},

 12     {'>','>','>','>','<','>','>'},

 13     {'>','>','>','>','<','>','>'},

 14     {'<','<','<','<','<','=','@'},

 15     {'>','>','>','>','@','>','>'},

 16     {'<','<','<','<','<','@','='}

 17 };

 18 char st_char[N];

 19 int st_int[N],top_char,top_int;

 20 int cal(int a,char op,int b)

 21 {

 22     switch(op)

 23     {

 24     case '+':

 25         return a+b;

 26         break;

 27     case '-':

 28         return a-b;

 29         break;

 30     case '*':

 31         return a*b;

 32         break;

 33     case '/':

 34         return a/b;

 35         break;

 36     default:

 37         while(1)puts("You Will Output Limit Exceeded\n");

 38     }

 39 }

 40 char comp(char a,char b)

 41 {

 42     int i,j;

 43     for(i=0; i<7; i++)

 44         if(a==op[i])

 45             break;

 46     for(j=0; j<7; j++)

 47         if(b==op[j])

 48             break;

 49     return cp[i][j];

 50 }

 51 char comp10(char x,char ch)

 52 {

 53      if(x=='+'||x=='-')

 54         if(ch=='+'||ch=='-'||ch==')'||ch=='\0') return ('>');

 55         else return ('<');

 56      if(x=='*'||x=='/')

 57         if(ch=='(') return('<');

 58         else return('>');

 59      if(x=='(')

 60         if(ch==')') return('=');

 61         else return('<');

 62      if(x==')')

 63         if(ch!='(') return('>');

 64      if(x=='\0')

 65         if(ch=='\0') return('=');

 66         else return('<');

 67 }

 68 int cac(char s[])

 69 {

 70     top_char=top_int=0;

 71     st_char[top_char++]='\0';

 72     int i=0,v,a,b;

 73     char ch;

 74     bool flag=true;

 75     while(s[i]!='\0'||st_char[top_char-1]!='\0')

 76     {

 77         if(s[i]==' '||s[i]=='\t')

 78         {

 79             i++;

 80             continue;

 81         }

 82         else if(isdigit(s[i]))

 83         {

 84             v=0;

 85             while(isdigit(s[i]))

 86             {

 87                 v=v*10+s[i]-'0';

 88                 i++;

 89             }

 90             st_int[top_int++]=v;

 91         }

 92         else if(isalpha(s[i]))

 93         {

 94             st_int[top_int++]=(int)s[i++];

 95         }

 96         else

 97         {

 98             switch(comp(st_char[top_char-1],s[i]))

 99             {

100             case '<':

101                 st_char[top_char++]=s[i++];

102                 break;

103             case '=':

104                 top_char--;

105                 i++;

106                 break;

107             case '>':

108                 ch=st_char[--top_char];

109                 b=st_int[--top_int];

110                 a=st_int[--top_int];

111                 v=cal(a,ch,b);

112                 st_int[top_int++]=v;

113                 break;

114             }

115         }

116     }

117     return st_int[0];

118 }

119 int main()

120 {

121     int T;

122     for(scanf("%d ",&T); T; T--)

123     {

124         char s1[1000],s2[1000];

125         gets(s1);

126         gets(s2);

127         if(cac(s1)==cac(s2))

128             printf("YES\n");

129         else

130             printf("NO\n");

131     }

132     return 0;

133 }