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Commit 90a1126

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feat: add python and java solutions to leetcode problem: No.0227
1 parent 3304a40 commit 90a1126

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6 files changed

+177
-48
lines changed

6 files changed

+177
-48
lines changed

‎README.md‎

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- [逆波兰表达式求值](/solution/0100-0199/0150.Evaluate%20Reverse%20Polish%20Notation/README.md)
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- [最近的请求次数](/solution/0900-0999/0933.Number%20of%20Recent%20Calls/README.md)
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- [每日温度](/solution/0700-0799/0739.Daily%20Temperatures/README.md)
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- [基本计算器 II](/solution/0200-0299/0227.Basic%20Calculator%20II/README.md)
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### 动态规划
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‎README_EN.md‎

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@@ -128,6 +128,7 @@ Complete solutions to [LeetCode](https://leetcode-cn.com/problemset/all/), [LCOF
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- [Evaluate Reverse Polish Notation](/solution/0100-0199/0150.Evaluate%20Reverse%20Polish%20Notation/README_EN.md)
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- [Number of Recent Calls](/solution/0900-0999/0933.Number%20of%20Recent%20Calls/README_EN.md)
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- [Daily Temperatures](/solution/0700-0799/0739.Daily%20Temperatures/README_EN.md)
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- [Basic Calculator II](/solution/0200-0299/0227.Basic%20Calculator%20II/README_EN.md)
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### Dynamic Programming
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‎solution/0200-0299/0227.Basic Calculator II/README.md‎

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<!-- 这里可写通用的实现逻辑 -->
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遍历字符串 s,并用变量 `preSign` 记录每个数字之前的运算符,对于第一个数字,其之前的运算符视为加号。每次遍历到数字末尾时,根据 `preSign` 来决定计算方式:
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- 加号:将数字压入栈;
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- 减号:将数字的相反数压入栈;
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- 乘除号:计算数字与栈顶元素,并将栈顶元素替换为计算结果。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def calculate(self, s: str) -> int:
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num, n = 0, len(s)
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pre_sign = '+'
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stack = []
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for i in range(n):
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if s[i].isdigit():
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num = num * 10 + int(s[i])
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if i == n - 1 or (not s[i].isdigit() and s[i] != ' '):
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if pre_sign == '+':
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stack.append(num)
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elif pre_sign == '-':
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stack.append(-num)
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elif pre_sign == '*':
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stack.append(stack.pop() * num)
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else:
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stack.append(int(stack.pop() / num))
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pre_sign = s[i]
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num = 0
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res = 0
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while stack:
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res += stack.pop()
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return res
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int calculate(String s) {
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int num = 0;
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char preSign = '+';
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Deque<Integer> stack = new ArrayDeque<>();
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for (int i = 0, n = s.length(); i < n; ++i) {
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if (Character.isDigit(s.charAt(i))) {
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num = num * 10 + (s.charAt(i) - '0');
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}
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if (i == n - 1 || (!Character.isDigit(s.charAt(i)) && s.charAt(i) != ' ')) {
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switch (preSign) {
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case '+':
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stack.push(num);
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break;
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case '-':
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stack.push(-num);
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break;
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case '*':
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stack.push(stack.pop() * num);
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break;
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case '/':
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stack.push(stack.pop() / num);
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break;
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}
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preSign = s.charAt(i);
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num = 0;
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}
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}
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int res = 0;
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while (!stack.isEmpty()) {
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res += stack.pop();
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}
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return res;
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}
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}
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```
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### **...**

‎solution/0200-0299/0227.Basic Calculator II/README_EN.md‎

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### **Python3**
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```python
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class Solution:
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def calculate(self, s: str) -> int:
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num, n = 0, len(s)
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pre_sign = '+'
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stack = []
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for i in range(n):
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if s[i].isdigit():
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num = num * 10 + int(s[i])
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if i == n - 1 or (not s[i].isdigit() and s[i] != ' '):
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if pre_sign == '+':
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stack.append(num)
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elif pre_sign == '-':
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stack.append(-num)
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elif pre_sign == '*':
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stack.append(stack.pop() * num)
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else:
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stack.append(int(stack.pop() / num))
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pre_sign = s[i]
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num = 0
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res = 0
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while stack:
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res += stack.pop()
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return res
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```
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### **Java**
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```java
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class Solution {
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public int calculate(String s) {
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int num = 0;
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char preSign = '+';
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Deque<Integer> stack = new ArrayDeque<>();
86+
for (int i = 0, n = s.length(); i < n; ++i) {
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if (Character.isDigit(s.charAt(i))) {
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num = num * 10 + (s.charAt(i) - '0');
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}
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if (i == n - 1 || (!Character.isDigit(s.charAt(i)) && s.charAt(i) != ' ')) {
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switch (preSign) {
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case '+':
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stack.push(num);
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break;
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case '-':
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stack.push(-num);
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break;
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case '*':
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stack.push(stack.pop() * num);
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break;
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case '/':
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stack.push(stack.pop() / num);
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break;
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}
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preSign = s.charAt(i);
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num = 0;
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}
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}
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int res = 0;
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while (!stack.isEmpty()) {
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res += stack.pop();
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}
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return res;
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}
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}
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```
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### **...**
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Original file line numberDiff line numberDiff line change
@@ -1,52 +1,36 @@
11
class Solution {
22
public int calculate(String s) {
3-
char[] cs = s.toCharArray();
4-
Deque<Character> op = new ArrayDeque<>();
5-
Deque<Integer> num = new ArrayDeque<>();
6-
for (int i = 0; i < cs.length; ++i) {
7-
if (cs[i] == '*' || cs[i] == '/') {
8-
op.push(cs[i]);
9-
} else if (cs[i] == '+' || cs[i] == '-') {
10-
if (!op.isEmpty()) {
11-
calc(op, num);
12-
}
13-
op.push(cs[i]);
14-
} else if (Character.isDigit(cs[i])) {
15-
int j = i;
16-
int k = 0;
17-
while (j < cs.length && Character.isDigit(cs[j])) {
18-
k = k * 10 + cs[j] - '0';
19-
++j;
20-
}
21-
i = j - 1;
22-
num.push(k);
23-
if (!op.isEmpty() && (op.peek() == '*' || op.peek() == '/')) {
24-
calc(op, num);
3+
int num = 0;
4+
char preSign = '+';
5+
Deque<Integer> stack = new ArrayDeque<>();
6+
for (int i = 0, n = s.length(); i < n; ++i) {
7+
if (Character.isDigit(s.charAt(i))) {
8+
num = num * 10 + (s.charAt(i) - '0');
9+
}
10+
if (i == n - 1 || (!Character.isDigit(s.charAt(i)) && s.charAt(i) != ' ')) {
11+
switch (preSign) {
12+
case '+':
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stack.push(num);
14+
break;
15+
case '-':
16+
stack.push(-num);
17+
break;
18+
case '*':
19+
stack.push(stack.pop() * num);
20+
break;
21+
case '/':
22+
stack.push(stack.pop() / num);
23+
break;
2524
}
25+
preSign = s.charAt(i);
26+
num = 0;
2627
}
2728
}
28-
if (!op.isEmpty()) {
29-
calc(op, num);
30-
}
31-
return num.peek();
32-
}
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34-
private void calc(Deque<Character> op, Deque<Integer> num) {
35-
int y = num.pop();
36-
int x = num.pop();
37-
switch (op.pop()) {
38-
case '*':
39-
num.push(x * y);
40-
break;
41-
case '/':
42-
num.push(x / y);
43-
break;
44-
case '+':
45-
num.push(x + y);
46-
break;
47-
default:
48-
num.push(x - y);
49-
break;
30+
int res = 0;
31+
while (!stack.isEmpty()) {
32+
res += stack.pop();
5033
}
34+
return res;
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}
52-
}
36+
}
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1+
class Solution:
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def calculate(self, s: str) -> int:
3+
num, n = 0, len(s)
4+
pre_sign = '+'
5+
stack = []
6+
for i in range(n):
7+
if s[i].isdigit():
8+
num = num * 10 + int(s[i])
9+
if i == n - 1 or (not s[i].isdigit() and s[i] != ' '):
10+
if pre_sign == '+':
11+
stack.append(num)
12+
elif pre_sign == '-':
13+
stack.append(-num)
14+
elif pre_sign == '*':
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stack.append(stack.pop() * num)
16+
else:
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stack.append(int(stack.pop() / num))
18+
pre_sign = s[i]
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num = 0
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res = 0
21+
while stack:
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res += stack.pop()
23+
return res

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