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BasicCalculatorII.java
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BasicCalculatorII.java
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package gracefulsoul.problems;
public class BasicCalculatorII {
// https://leetcode.com/submissions/detail/580763966/
public static void main(String[] args) {
BasicCalculatorII test = new BasicCalculatorII();
System.out.println(test.calculate("3+2*2"));
System.out.println(test.calculate(" 3/2 "));
System.out.println(test.calculate(" 3+5 / 2 "));
}
public int calculate(String s) {
int sum = 0;
int pre = 0;
char sign = '+';
for (int idx = 0; idx < s.length(); idx++) {
char c = s.charAt(idx);
if (c == ' ') {
continue;
} else if (Character.isDigit(c)) {
int num = c - '0';
while (idx < s.length() - 1 && Character.isDigit(s.charAt(idx + 1))) {
num = num * 10 + (s.charAt(idx + 1) - '0');
idx++;
}
switch (sign) {
case '+':
sum += pre;
pre = num;
break;
case '-':
sum += pre;
pre = -num;
break;
case '*':
pre *= num;
break;
case '/':
pre /= num;
break;
}
} else {
sign = c;
}
}
return sum + pre;
}
}