2022-11-20-21:33:57

Author: lifeiyang

leetcode/editor/cn/[241]为运算表达式设计优先级.py

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+from typing import List
+
+
+# leetcode submit region begin(Prohibit modification and deletion)
+class Solution:
+    def diffWaysToCompute(self, expression: str) -> List[int]:
+        res = []
+        for idx, c in enumerate(expression):
+            if c in ["*", "-", "+"]:
+                left_list = self.diffWaysToCompute(expression[:idx])
+                right_list = self.diffWaysToCompute(expression[idx + 1:])
+                for left in left_list:
+                    for right in right_list:
+                        if c == "*":
+                            res.append(left * right)
+                        if c == "-":
+                            res.append(left - right)
+                        if c == "+":
+                            res.append(left + right)
+        
+        if len(res) == 0:
+            # 说明其中没有 * - + 等符号，纯数字
+            res.append(int(expression))
+        return res
+
+
+# leetcode submit region end(Prohibit modification and deletion)
+
+if __name__ == "__main__":
+    solution = Solution()
+    print(solution.diffWaysToCompute("2*3-4*5"))

leetcode/editor/cn/doc/content/[241]为运算表达式设计优先级.md

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+<p>给你一个由数字和运算符组成的字符串&nbsp;<code>expression</code> ，按不同优先级组合数字和运算符，计算并返回所有可能组合的结果。你可以 <strong>按任意顺序</strong> 返回答案。</p>
+
+<p>生成的测试用例满足其对应输出值符合 32 位整数范围，不同结果的数量不超过 <code>10<sup>4</sup></code> 。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>expression = "2-1-1"
+<strong>输出：</strong>[0,2]
+<strong>解释：</strong>
+((2-1)-1) = 0 
+(2-(1-1)) = 2
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>expression = "2*3-4*5"
+<strong>输出：</strong>[-34,-14,-10,-10,10]
+<strong>解释：</strong>
+(2*(3-(4*5))) = -34 
+((2*3)-(4*5)) = -14 
+((2*(3-4))*5) = -10 
+(2*((3-4)*5)) = -10 
+(((2*3)-4)*5) = 10
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul> 
+ <li><code>1 &lt;= expression.length &lt;= 20</code></li> 
+ <li><code>expression</code> 由数字和算符 <code>'+'</code>、<code>'-'</code> 和 <code>'*'</code> 组成。</li> 
+ <li>输入表达式中的所有整数值在范围 <code>[0, 99]</code>&nbsp;</li> 
+</ul>
+
+<div><div>Related Topics</div><div><li>递归</li><li>记忆化搜索</li><li>数学</li><li>字符串</li><li>动态规划</li></div></div><br><div><li>👍 767</li><li>👎 0</li></div>