help "Runtime Error"

Question

My code could work in visual studio, but leetcode report "Runtime Error Last executed input: "]" ".

    bool isValid(string s) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
   // s1 store (), s2 store [], s3 store {}
    stack<char> s1; stack<char> s2; stack<char> s3;
    for(int i=0;i<s.length();i++)
    {
        switch(s[i]){
            case '(':s1.push('(');break;
            case ')':if(s1.top()=='(')s1.pop();else return false;break;
            case '[':if(s1.empty())s2.push('[');else return false;break;
            case ']':if(s1.empty()&&s2.top()=='[')s2.pop();else return false;break;
            case '{':if(s1.empty()&&s2.empty())s3.push('{');else return false;break;
            case '}':if(s1.empty()&&s2.empty()&&s3.top()=='{')s3.pop();else return false;break;
            default: return false;
        }
    }
    if(s1.empty()&&s2.empty()&&s3.empty())return true;
    else return false;
}

Comments

actually only one stack is enough

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Hello .I am having trouble solving this problem . Can you share your one stack solution? Thank U so much.

Answer 1

Because according to your conditional statement:

if(s1.empty()&&s2.top()=='[')

You are trying s2.top() when the s2 is empty, which caused the runtime error.