Create 227.Basic-Calculator-II.cpp

Author: wisdompeak

Stack/227.Basic-Calculator-II/227.Basic-Calculator-II.cpp

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+class Solution {
+public:
+ int calculate(string s) 
+ {
+ string S = "+";
+ for (auto ch:s)
+ {
+ if (ch==' ') continue;
+ S.push_back(ch);
+ if (ch=='(')
+ S+="+";
+ }
+ s = S;
+
+ vector<int>nums;
+ vector<int>signs;
+ int sign;
+
+ for (int i=0; i<S.size(); i++)
+ {
+ if (s[i]=='+' || s[i]=='-')
+ {
+ signs.push_back(s[i]=='+'?1:-1);
+ }
+ else if (s[i]=='*' || s[i]=='/')
+ {
+ int j = i+1;
+ while (j<s.size() && isdigit(s[j]))
+ j++;
+ int num = stoi(s.substr(i+1,j-i-1)); 
+ if (s[i]=='*') nums.back() *= num;
+ else if (s[i]=='/') nums.back() /= num;
+ i = j-1;
+ }
+ else if (isdigit(s[i]))
+ {
+ int j = i;
+ while (j<s.size() && isdigit(s[j]))
+ j++;
+ int num = stoi(s.substr(i,j-i)); 
+ nums.push_back(num);
+ i = j-1;
+ }
+ }
+
+ int ret = 0;
+ for (int i=0; i<nums.size(); i++)
+ ret+=nums[i]*signs[i];
+ return ret;
+ }
+};