问题
Given an expression string exp. Examine whether the pairs and the orders of “{“,”}”,”(“,”)”,”[“,”]” are correct in exp.
For example, the program should print 'balanced' for exp = “[()]{}{[()()]()}” and 'not balanced' for exp = “[(])”
Input
The first line of input contains an integer T denoting the number of test cases. Each test case consists of a string of expression, in a separate line.
Output
Print 'balanced' without quotes if the pair of parenthesis is balanced else print 'not balanced' in a separate line.
Constraints
1 ≤ T ≤ 100
1 ≤ |s| ≤ 105
Example
Input:
3
{([])}
()
([]
Output
balanced
balanced
not balanced
#include <iostream>
#include <cstring>
#include <stack>
using namespace std;
int main() {
//code
int t;cin>>t;
while(t--) {
string s;
stack<char> st;
int i=0,flag =1;
getline(cin,s);
int n = s.size();
while(s[i] != '\0') {
if((s[i] == '{') || (s[i] == '[') || (s[i] == '(')) {
st.push(s[i]);
}
else if(!st.empty() && ((st.top() == '{' && s[i] == '}') ||
(st.top() == '[' && s[i] == ']') || (st.top() == '(' && s[i] == ')'))) st.pop();
else {
flag = 0;
break;
}
i++;
}
(st.empty() && flag) ? cout<<"balanced\n" : cout<<"not balanced\n";
}
return 0;
}
回答1:
Stepping through your code with a debugger, the first time through the loop your string is empty.
This is because cin >> t stops reading at the newline character of the first line, and the first getline(cin, s) line receives an empty string.
Simply call getline(cin, dummy_string) after cin >> t to read the rest of the line, or switch your loop to use cin >> s instead.
来源：https://stackoverflow.com/questions/61792911/test-case-incorrect-for-paranthesis-checker-code-for-output-sould-be-not