|
| 1 | +--- |
| 2 | +id: check-if-there-is-a-valid-parenthesis-string-path |
| 3 | +title: Check If there is a Valid Parenthesis String Path |
| 4 | +sidebar_label: 2267-Check If there is a Valid Parenthesis String Path |
| 5 | +tags: |
| 6 | + - Valid Parentheses Path |
| 7 | + - Brute Force |
| 8 | + - Optimized |
| 9 | + - LeetCode |
| 10 | + - Java |
| 11 | + - Python |
| 12 | + - C++ |
| 13 | +description: "This is a solution to the Valid Parentheses Path problem on LeetCode." |
| 14 | +sidebar_position: 2 |
| 15 | +--- |
| 16 | + |
| 17 | +In this tutorial, we will solve the Valid Parentheses Path problem using two different approaches: brute force and optimized. We will provide the implementation of the solution in C++, Java, and Python. |
| 18 | + |
| 19 | +## Problem Description |
| 20 | + |
| 21 | +Given an m x n matrix of parentheses grid, a valid parentheses string path in the grid is a path satisfying all of the following conditions: |
| 22 | + |
| 23 | +- The path starts from the upper left cell (0, 0). |
| 24 | +- The path ends at the bottom-right cell (m - 1, n - 1). |
| 25 | +- The path only ever moves down or right. |
| 26 | +- The resulting parentheses string formed by the path is valid. |
| 27 | + |
| 28 | +Return true if there exists a valid parentheses string path in the grid. Otherwise, return false. |
| 29 | + |
| 30 | +### Examples |
| 31 | + |
| 32 | +**Example 1:** |
| 33 | + |
| 34 | +``` |
| 35 | +Input: grid = [["(","(","("],[")","(",")"],["(","(",")"],["(","(",")"]] |
| 36 | +Output: true |
| 37 | +Explanation: The above diagram shows two possible paths that form valid parentheses strings. |
| 38 | +The first path shown results in the valid parentheses string "()(())". |
| 39 | +The second path shown results in the valid parentheses string "((()))". |
| 40 | +Note that there may be other valid parentheses string paths. |
| 41 | +``` |
| 42 | + |
| 43 | +**Example 2:** |
| 44 | + |
| 45 | +``` |
| 46 | +Input: grid = [[")",")"],["(","("]] |
| 47 | +Output: false |
| 48 | +Explanation: The two possible paths form the parentheses strings "))(" and ")((". Since neither of them are valid parentheses strings, we return false. |
| 49 | +
|
| 50 | +``` |
| 51 | + |
| 52 | +### Constraints |
| 53 | + |
| 54 | +- `m == grid.length` |
| 55 | +- `n == grid[i].length` |
| 56 | +- `1 <= m, n <= 100` |
| 57 | +- `grid[i][j]` is either '(' or ')'. |
| 58 | + |
| 59 | +--- |
| 60 | + |
| 61 | +## Solution for Valid Parentheses Path Problem |
| 62 | + |
| 63 | +### Intuition and Approach |
| 64 | + |
| 65 | +The problem can be solved using a brute force approach or an optimized approach. The brute force approach directly explores all possible paths, while the optimized approach uses dynamic programming to efficiently check valid paths. |
| 66 | + |
| 67 | +<Tabs> |
| 68 | +<tabItem value="Brute Force" label="Brute Force"> |
| 69 | + |
| 70 | +### Approach 1: Brute Force (Naive) |
| 71 | + |
| 72 | +The brute force approach recursively explores all possible paths from the top-left to the bottom-right cell, ensuring the parentheses string remains valid. |
| 73 | + |
| 74 | +#### Code in Different Languages |
| 75 | + |
| 76 | +<Tabs> |
| 77 | +<TabItem value="C++" label="C++" default> |
| 78 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 79 | + |
| 80 | +```cpp |
| 81 | +class Solution { |
| 82 | +public: |
| 83 | + bool isValidPath(vector<vector<char>>& grid, int i, int j, int balance) { |
| 84 | + if (i >= grid.size() || j >= grid[0].size() || balance < 0) return false; |
| 85 | + balance += (grid[i][j] == '(') ? 1 : -1; |
| 86 | + if (i == grid.size() - 1 && j == grid[0].size() - 1) return balance == 0; |
| 87 | + return isValidPath(grid, i + 1, j, balance) || isValidPath(grid, i, j + 1, balance); |
| 88 | + } |
| 89 | + |
| 90 | + bool hasValidPath(vector<vector<char>>& grid) { |
| 91 | + return isValidPath(grid, 0, 0, 0); |
| 92 | + } |
| 93 | +}; |
| 94 | +``` |
| 95 | +
|
| 96 | +</TabItem> |
| 97 | +<TabItem value="Java" label="Java"> |
| 98 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 99 | +
|
| 100 | +```java |
| 101 | +class Solution { |
| 102 | + public boolean isValidPath(char[][] grid, int i, int j, int balance) { |
| 103 | + if (i >= grid.length || j >= grid[0].length || balance < 0) return false; |
| 104 | + balance += (grid[i][j] == '(') ? 1 : -1; |
| 105 | + if (i == grid.length - 1 && j == grid[0].length - 1) return balance == 0; |
| 106 | + return isValidPath(grid, i + 1, j, balance) || isValidPath(grid, i, j + 1, balance); |
| 107 | + } |
| 108 | + |
| 109 | + public boolean hasValidPath(char[][] grid) { |
| 110 | + return isValidPath(grid, 0, 0, 0); |
| 111 | + } |
| 112 | +} |
| 113 | +``` |
| 114 | + |
| 115 | +</TabItem> |
| 116 | +<TabItem value="Python" label="Python"> |
| 117 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 118 | + |
| 119 | +```python |
| 120 | +class Solution: |
| 121 | + def isValidPath(self, grid: List[List[str]], i: int, j: int, balance: int) -> bool: |
| 122 | + if i >= len(grid) or j >= len(grid[0]) or balance < 0: |
| 123 | + return False |
| 124 | + balance += 1 if grid[i][j] == '(' else -1 |
| 125 | + if i == len(grid) - 1 and j == len(grid[0]) - 1: |
| 126 | + return balance == 0 |
| 127 | + return self.isValidPath(grid, i + 1, j, balance) or self.isValidPath(grid, i, j + 1, balance) |
| 128 | + |
| 129 | + def hasValidPath(self, grid: List[List[str]]) -> bool: |
| 130 | + return self.isValidPath(grid, 0, 0, 0) |
| 131 | +``` |
| 132 | + |
| 133 | +</TabItem> |
| 134 | +</Tabs> |
| 135 | + |
| 136 | +#### Complexity Analysis |
| 137 | + |
| 138 | +- Time Complexity: Exponential due to exploring all paths. |
| 139 | +- Space Complexity: Exponential due to recursive call stack. |
| 140 | +- The brute force approach is inefficient for larger grids. |
| 141 | + |
| 142 | +</tabItem> |
| 143 | +<tabItem value="Optimized" label="Optimized"> |
| 144 | + |
| 145 | +### Approach 2: Optimized Approach |
| 146 | + |
| 147 | +The optimized approach uses dynamic programming to track valid paths with different balances at each cell. This significantly reduces redundant calculations. |
| 148 | + |
| 149 | +#### Code in Different Languages |
| 150 | + |
| 151 | +<Tabs> |
| 152 | +<TabItem value="C++" label="C++" default> |
| 153 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 154 | + |
| 155 | +```cpp |
| 156 | +class Solution { |
| 157 | +public: |
| 158 | + bool hasValidPath(vector<vector<char>>& grid) { |
| 159 | + int m = grid.size(), n = grid[0].size(); |
| 160 | + if (grid[0][0] == ')') return false; |
| 161 | + vector<vector<vector<bool>>> dp(m, vector<vector<bool>>(n, vector<bool>(m + n, false))); |
| 162 | + dp[0][0][1] = true; |
| 163 | + |
| 164 | + for (int i = 0; i < m; ++i) { |
| 165 | + for (int j = 0; j < n; ++j) { |
| 166 | + for (int k = 0; k <= m + n; ++k) { |
| 167 | + if (dp[i][j][k]) { |
| 168 | + if (i + 1 < m) { |
| 169 | + int new_balance = k + (grid[i + 1][j] == '(' ? 1 : -1); |
| 170 | + if (new_balance >= 0 && new_balance <= m + n) { |
| 171 | + dp[i + 1][j][new_balance] = true; |
| 172 | + } |
| 173 | + } |
| 174 | + if (j + 1 < n) { |
| 175 | + int new_balance = k + (grid[i][j + 1] == '(' ? 1 : -1); |
| 176 | + if (new_balance >= 0 && new_balance <= m + n) { |
| 177 | + dp[i][j + 1][new_balance] = true; |
| 178 | + } |
| 179 | + } |
| 180 | + } |
| 181 | + } |
| 182 | + } |
| 183 | + } |
| 184 | + |
| 185 | + return dp[m - 1][n - 1][0]; |
| 186 | + } |
| 187 | +}; |
| 188 | +``` |
| 189 | +
|
| 190 | +</TabItem> |
| 191 | +<TabItem value="Java" label="Java"> |
| 192 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 193 | +
|
| 194 | +```java |
| 195 | +class Solution { |
| 196 | + public boolean hasValidPath(char[][] grid) { |
| 197 | + int m = grid.length, n = grid[0].length; |
| 198 | + if (grid[0][0] == ')') return false; |
| 199 | + boolean[][][] dp = new boolean[m][n][m + n]; |
| 200 | + dp[0][0][1] = true; |
| 201 | + |
| 202 | + for (int i = 0; i < m; ++i) { |
| 203 | + for (int j = 0; j < n; ++j) { |
| 204 | + for (int k = 0; k <= m + n; ++k) { |
| 205 | + if (dp[i][j][k]) { |
| 206 | + if (i + 1 < m) { |
| 207 | + int new_balance = k + (grid[i + 1][j] == '(' ? 1 : -1); |
| 208 | + if (new_balance >= 0 && new_balance <= m + n) { |
| 209 | + dp[i + 1][j][new_balance] = true; |
| 210 | + } |
| 211 | + } |
| 212 | + if (j + 1 < n) { |
| 213 | + int new_balance = k + (grid[i][j + 1] == '(' ? 1 : -1); |
| 214 | + if (new_balance >= 0 && new_balance <= m + n) { |
| 215 | + dp[i][j + 1][new_balance] = true; |
| 216 | + } |
| 217 | + } |
| 218 | + } |
| 219 | + } |
| 220 | + } |
| 221 | + } |
| 222 | + |
| 223 | + return dp[m - 1][n - 1][0]; |
| 224 | + } |
| 225 | +} |
| 226 | +``` |
| 227 | + |
| 228 | +</TabItem> |
| 229 | +<TabItem value="Python" label="Python"> |
| 230 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 231 | + |
| 232 | +```python |
| 233 | +class Solution: |
| 234 | + def hasValidPath(self, grid: List[List[str]]) -> bool: |
| 235 | + m, n = len(grid), len(grid[0]) |
| 236 | + if grid[0][0] == ')': |
| 237 | + return False |
| 238 | + dp = [[[False] * (m + n) for _ in range(n)] for _ in range(m)] |
| 239 | + dp[0][0][1] = True |
| 240 | + |
| 241 | + for i in range(m): |
| 242 | + for j in range(n): |
| 243 | + for k in range(m + n): |
| 244 | + if dp[i][j][k]: |
| 245 | + if i + 1 < m: |
| 246 | + new_balance = k + (1 if grid[i + 1][j] == '(' else -1) |
| 247 | + if 0 <= new_balance <= m + n: |
| 248 | + dp[i + 1][j][new_balance] = True |
| 249 | + if j + 1 < n: |
| 250 | + new_balance = k + (1 if grid[i][j + 1] == '(' else -1) |
| 251 | + if 0 <= new_balance <= m + n: |
| 252 | + dp[i][j + 1][new_balance] = True |
| 253 | + |
| 254 | + return dp[m - 1][n - 1][0] |
| 255 | +``` |
| 256 | + |
| 257 | +</TabItem> |
| 258 | +</Tabs> |
| 259 | + |
| 260 | +#### Complexity Analysis |
| 261 | + |
| 262 | +- Time Complexity: $O( (m + n))$ |
| 263 | +- Space Complexity: $O( (m + n))$ |
| 264 | +- Where `m` is the number of rows and `n` is the number of columns. |
| 265 | +- The optimized approach efficiently tracks valid paths using dynamic programming. |
| 266 | + |
| 267 | +</tabItem> |
| 268 | +</Tabs> |
| 269 | + |
| 270 | +--- |
| 271 | + |
| 272 | +<h2>Authors:</h2> |
| 273 | + |
| 274 | +<div style={{display: 'flex', flexWrap: 'wrap', justifyContent: 'space-between', gap: '10px'}}> |
| 275 | +{['ImmidiSivani'].map(username => ( |
| 276 | + <Author key={username} username={username} /> |
| 277 | +))} |
| 278 | +</div> |
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