# Removal of redundant expression inside ()

2010-05-31  来源：本站原创  分类：Tech  人气：284

This is a long time ago a friend asked me CSDN's a question:

Removal of redundant expression inside ()
Check whether the string matches the expression in parentheses;
The number of left parentheses is not equal with the number in brackets shall be no match;
Remove the extra left bracket or right bracket, the priority appears to retain the first bracket;
Matching parentheses after the removal of invalid: such as: ((expression)) should be (expression);
Consider only small brackets, do not appear to consider the first case the right parenthesis;
Required to achieve the function: (string up to length 60; expression need not consider the correctness)
void Bracket (char * src, char * dst);

If the match is output through the original string dst;

If you do not place more than match the brackets under requirements adopted after the dst string after the output matching

Example input: 12 + (345 * 25-34) output: 12 + (345 * 25-34)

Enter: 12 + (345 * (25-34) output: 12 + (345 * 25-34)

Input: (12 +345) * 25) -34 Output: (12 +345) * 25-34

Enter: (543 + (256-43) * 203)) +24 Output: (543 + (256-43) * 203) +24

Input: ((1 +2) * ((34-2 ))+(( 2 * 8-1) Output: ((1 +2) * (34-2) +2 * 8-1)

```#include <stdio.h>
#include <iostream>
#include <string.h>
#include <stack>
#define maxv(a, b) ((a) >= (b) ? (a) : (b))
#define minv(a, b) ((a) <= (b) ? (a) : (b))
#define MAX_N 60
using namespace std;
bool unValid[MAX_N + 1];
char input[MAX_N + 1];
char output[MAX_N + 1];
int len;
int lp[MAX_N + 1];
int rp[MAX_N + 1];
struct para
{
char type;
int pos;
para(char t, int p)
{
type = t;
pos = p;
}
};
stack<para> pStack;
void Bracket(char* src, char* dst)
{
int i;
// Extraneous closing parenthesis
if(lp[0] < rp[0])
{
for(i = rp[0]; i >= lp[0] + 1; i--)
{
unValid[rp] = true;
rp = -1;
}
}
// Extraneous left parenthesis
else if(lp[0] > rp[0])
{
for(i = lp[0]; i >= rp[0] + 1; i--)
{
unValid[lp] = true;
lp = -1;
}
}
// Matching parentheses after removing invalid  : If  :(( Expression  ))  Should be  ( Expression  )
for(i = 0; i < len; i++)
{
if(input == '(' && !unValid)
{
while(pStack.size() >= 1 && pStack.top().type == ')')
pStack.pop();
pStack.push(para('(', i));
}
else if(input == ')' && !unValid)
{
if(pStack.size() >= 3)
{
para p1 = pStack.top();
if(p1.type == ')')
{
pStack.pop();
para p2 = pStack.top();
pStack.pop();
para p3 = pStack.top();
pStack.pop();
if(p1.type == ')' && p2.type == '(' && p3.type == '(' && p2.pos - p3.pos == 1 && i - p1.pos == 1)
{
unValid[p1.pos] = true;
unValid[p2.pos] = true;
}
pStack.push(p3);
}
}
pStack.push(para(')', i));
}
}

int k = 0;
for(i = 0; i < len; i++)
{
if(!unValid)
{
dst[k++] = input;
}
}
dst[k] = '\0';
}
int main()
{
char ch;
while((ch = getchar()) != 10)
{
input[len++] = ch;
if(ch == '(')
{
lp[0]++;
lp[lp[0]] = len - 1;
}
else if(ch == ')')
{
rp[0]++;
rp[rp[0]] = len - 1;
}
}
Bracket(input, output);
printf("%s\n", output);
return 0;
}
```

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