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s1.cpp
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s1.cpp
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// OJ: https://leetcode.com/problems/basic-calculator-iv
// Author: github.com/lzl124631x
class Solution {
private:
vector<string> tokenize(string &expression) {
vector<string> tokens;
for (int i = 0; i < expression.size();) {
string token;
if (isalnum(expression[i])) {
while (i < expression.size() && isalnum(expression[i])) {
token += expression[i++];
}
} else token += expression[i++];
tokens.push_back(token);
while (i < expression.size() && expression[i] == ' ') ++i;
}
return tokens;
}
vector<string> inject(vector<string> &tokens, unordered_map<string, string> &m) {
for (auto &token : tokens) {
if (m.find(token) != m.end()) token = m[token];
}
return tokens;
}
vector<string> toRPN(vector<string> &tokens) {
stack<string> ops;
vector<string> ans;
for (auto &token : tokens) {
switch(token.back()) {
case '+':
case '-':
while (ops.size() && ops.top() != "(") {
ans.push_back(ops.top());
ops.pop();
}
ops.push(token);
break;
case '*':
if (ops.size() && ops.top() == "*") {
ans.push_back(ops.top());
ops.pop();
}
ops.push(token);
break;
case '(':
ops.push(token);
break;
case ')':
while (ops.size() && ops.top() != "(") {
ans.push_back(ops.top());
ops.pop();
}
if (ops.size()) ops.pop();
break;
default:
ans.push_back(token);
break;
}
}
while (ops.size()) {
ans.push_back(ops.top());
ops.pop();
}
return ans;
}
vector<string> splitSymbols(string exp) {
istringstream s(exp);
vector<string> ans;
string symbol;
while (getline(s, symbol, '*')) ans.push_back(symbol);
return ans;
}
vector<string> evaluate(vector<string> &tokens) {
stack<map<string, int>> s;
for (auto &token : tokens) {
switch(token.back()) {
case '+':
case '-': {
int sign = token[0] == '+' ? 1 : -1;
auto b = s.top(); s.pop();
auto a = s.top(); s.pop();
map<string, int> m;
for (auto &p : a) {
m[p.first] += p.second;
}
for (auto &p : b) {
m[p.first] += sign * p.second;
}
s.push(m);
break;
}
case '*': {
auto b = s.top(); s.pop();
auto a = s.top(); s.pop();
map<string, int> m;
for (auto &p : a) {
auto symbol1 = splitSymbols(p.first);
for (auto &q : b) {
istringstream sb(q.first);
auto symbol2 = splitSymbols(q.first);
string symbol;
if (symbol1.size() == 1 && symbol1[0] == "1") {
symbol = q.first;
} else if (symbol2.size() == 1 && symbol2[0] == "1") {
symbol = p.first;
} else {
for (int i = 0, j = 0; i < symbol1.size() || j < symbol2.size();) {
if (symbol.size()) symbol += "*";
if (i >= symbol1.size()) {
symbol += symbol2[j++];
} else if (j >= symbol2.size()) {
symbol += symbol1[i++];
} else if (symbol1[i] < symbol2[j]){
symbol += symbol1[i++];
} else {
symbol += symbol2[j++];
}
}
}
m[symbol] += p.second * q.second;
}
}
s.push(m);
break;
}
default: {
map<string, int> m;
if (isdigit(token.back())) {
m["1"] = stoi(token);
} else {
m[token] = 1;
}
s.push(m);
break;
}
}
}
vector<string> ans;
for (auto &p : s.top()) {
if (!p.second) continue;
ans.push_back(to_string(p.second) + (p.first == "1" ? "" : "*" + p.first));
}
stable_sort(ans.begin(), ans.end(), [&](string a, string b) {
return count(a.begin(), a.end(), '*') > count(b.begin(), b.end(), '*');
});
return ans;
}
public:
vector<string> basicCalculatorIV(string expression, vector<string>& evalvars, vector<int>& evalints) {
unordered_map<string, string> m;
for (int i = 0; i < evalvars.size(); ++i) {
m[evalvars[i]] = to_string(evalints[i]);
}
auto tokens = tokenize(expression);
tokens = inject(tokens, m);
tokens = toRPN(tokens);
tokens = evaluate(tokens);
return tokens;
}
};