leetcode - 2232. Minimize Result by Adding Parentheses to Expression

Description

You are given a 0-indexed string expression of the form "+" where and represent positive integers.

Add a pair of parentheses to expression such that after the addition of parentheses, expression is a valid mathematical expression and evaluates to the smallest possible value. The left parenthesis must be added to the left of '+' and the right parenthesis must be added to the right of '+'.

Return expression after adding a pair of parentheses such that expression evaluates to the smallest possible value. If there are multiple answers that yield the same result, return any of them.

The input has been generated such that the original value of expression, and the value of expression after adding any pair of parentheses that meets the requirements fits within a signed 32-bit integer.

Example 1:

复制代码
Input: expression = "247+38"
Output: "2(47+38)"
Explanation: The expression evaluates to 2 * (47 + 38) = 2 * 85 = 170.
Note that "2(4)7+38" is invalid because the right parenthesis must be to the right of the '+'.
It can be shown that 170 is the smallest possible value.

Example 2:

复制代码
Input: expression = "12+34"
Output: "1(2+3)4"
Explanation: The expression evaluates to 1 * (2 + 3) * 4 = 1 * 5 * 4 = 20.

Example 3:

复制代码
Input: expression = "999+999"
Output: "(999+999)"
Explanation: The expression evaluates to 999 + 999 = 1998.

Constraints:

复制代码
3 <= expression.length <= 10
expression consists of digits from '1' to '9' and '+'.
expression starts and ends with digits.
expression contains exactly one '+'.
The original value of expression, and the value of expression after adding any pair of parentheses that meets the requirements fits within a signed 32-bit integer.

Solution

Try every possible position to put the parentheses.

Time complexity: o ( n 2 ) o(n^2) o(n2)

Space complexity: o ( 1 ) o(1) o(1)

Code

python3 复制代码
class Solution:
    def minimizeResult(self, expression: str) -> str:
        def get_value_from_expression(expression: str) -> int:
            left, right = expression.find('('), expression.find(')')
            res = eval(expression[left + 1: right])
            if left == 0 and right == len(expression) - 1:
                pass
            elif left == 0:
                res *= int(expression[right + 1:])
            elif right == len(expression) - 1:
                res *= int(expression[:left])
            else:
                res *= int(expression[:left]) * int(expression[right + 1:])
            return res

        left_index = []
        right_index = []
        add_index = expression.find('+')
        for i in range(len(expression)):
            if i < add_index:
                left_index.append(i)
            elif i > add_index:
                right_index.append(i + 1)
        min_val = float('inf')
        res = ''
        for l in left_index:
            for r in right_index:
                cur_expression = f'{expression[:l]}({expression[l:r]}){expression[r:]}'
                cur_value = get_value_from_expression(cur_expression)
                if cur_value < min_val:
                    min_val = cur_value
                    res = cur_expression
        return res
相关推荐
workflower1 小时前
微软PM的来历
java·开发语言·算法·microsoft·django·结对编程
JianminZheng4 小时前
MTPA算法原理及仿真验证
算法
im_AMBER4 小时前
Leetcode 38
笔记·学习·算法·leetcode
Miraitowa_cheems5 小时前
LeetCode算法日记 - Day 82: 环形子数组的最大和
java·数据结构·算法·leetcode·决策树·线性回归·深度优先
Code_Shark5 小时前
AtCoder Beginner Contest 426 题解
数据结构·c++·算法·数学建模·青少年编程
仰泳的熊猫5 小时前
LeetCode:698. 划分为k个相等的子集
数据结构·c++·算法·leetcode
豐儀麟阁贵5 小时前
4.5数组排序算法
java·开发语言·数据结构·算法·排序算法
Shinom1ya_6 小时前
算法 day 32
算法
WBluuue7 小时前
数据结构与算法:摩尔投票算法
c++·算法·leetcode
2401_858286117 小时前
OS36.【Linux】简单理解EXT2文件系统(2)
linux·运维·服务器·数据结构·文件系统·ext2