57 lines
1.2 KiB
C++
57 lines
1.2 KiB
C++
#include <string>
|
|
|
|
class Solution {
|
|
public:
|
|
static int calculate(const std::string& s) {
|
|
int ret = 0;
|
|
char op = '+', prevOp = '+';
|
|
int n = 0, mid = 0;
|
|
for (const char c : s) {
|
|
if (c >= 0x30 && c <= 0x39) { n = (n << 3) + (n << 1) + (c ^ 48); }
|
|
else if (c == '+' || c == '-') {
|
|
switch (op) {
|
|
case '+':
|
|
ret += n; break;
|
|
case '-':
|
|
ret -= n; break;
|
|
case '*':
|
|
mid *= n; ret += prevOp == '+' ? mid : -mid; break;
|
|
case '/':
|
|
mid /= n; ret += prevOp == '+' ? mid : -mid; break;
|
|
default: exit(114514);
|
|
}
|
|
n = 0; op = c;
|
|
} else if (c == '*' || c == '/') {
|
|
switch (op) {
|
|
case '+':
|
|
case '-':
|
|
prevOp = op; mid = n; break;
|
|
case '*':
|
|
mid *= n; break;
|
|
case '/':
|
|
mid /= n; break;
|
|
default: exit(1919810);
|
|
}
|
|
n = 0; op = c;
|
|
}
|
|
}
|
|
switch (op) {
|
|
case '+':
|
|
ret += n; break;
|
|
case '-':
|
|
ret -= n; break;
|
|
case '*':
|
|
mid *= n; ret += prevOp == '+' ? mid : -mid; break;
|
|
case '/':
|
|
mid /= n; ret += prevOp == '+' ? mid : -mid; break;
|
|
default: exit(114514);
|
|
}
|
|
return ret;
|
|
}
|
|
};
|
|
|
|
int main() {
|
|
std::printf("%d\n", Solution::calculate("-1-2*3+4/5"));
|
|
return 0;
|
|
}
|