Basic Calculator III

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Problem Description

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Solutions

Solution 1: C# (Best: 72 ms)

Metric	Value
Runtime	72 ms
Memory	37.1 MB
Date	2022-01-25

Solution

public class Solution {
    public int Calculate(string s) {
        if(string.IsNullOrEmpty(s)) return 0;
    Stack<int> st = new Stack<int>();
    int current =0; char sign = '+';
    int n = s.Length;
    for (int i = 0; i < n; i++)
    {
        char c = s[i];
        if
        (char.IsDigit(c))
        {
            current = current*10 + (s[i]-'0');
        }
        else if(c == '(')
        {
            int j = i+1, braces = 1;
            for(;j<n;j++)
            {
                if(s[j] == '(') ++braces;
                if(s[j] == ')') --braces;
                if(braces == 0) break;
            }
            current = Calculate(s.Substring(i+1,j-i));
            i=j;
        }
        
        if(c == '+' || c == '-' || c == '*' || c == '/' || i == n-1)
        {
            if(sign == '+') st.Push(current);
            if(sign == '-') st.Push(-current);
            if(sign == '*') st.Push(st.Pop()*current);
            if(sign=='/') st.Push(st.Pop()/current);
            sign = c;
            current = 0;
        }
    }
    
    return st.Sum();
    }
}

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Complexity Analysis

Approach	Time	Space
Solution	To be analyzed	To be analyzed