|
| 1 | +--- |
| 2 | +id: string-compression |
| 3 | +title: String Compression Solution |
| 4 | +sidebar_label: String Compression |
| 5 | +tags: |
| 6 | + - String Compression |
| 7 | + - Brute Force |
| 8 | + - Optimized |
| 9 | + - LeetCode |
| 10 | + - Java |
| 11 | + - Python |
| 12 | + - C++ |
| 13 | +description: "This is a solution to the String Compression problem on LeetCode." |
| 14 | +sidebar_position: 2 |
| 15 | +--- |
| 16 | + |
| 17 | +In this tutorial, we will solve the String Compression 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 a string `word`, compress it using the following algorithm: |
| 22 | + |
| 23 | +Begin with an empty string `comp`. While `word` is not empty, use the following operation: |
| 24 | +Remove a maximum length prefix of `word` made of a single character `c` repeating at most 9 times. |
| 25 | +Append the length of the prefix followed by `c` to `comp`. |
| 26 | + |
| 27 | +Return the string `comp`. |
| 28 | + |
| 29 | +### Examples |
| 30 | + |
| 31 | +**Example 1:** |
| 32 | + |
| 33 | +``` |
| 34 | +Input: word = "abcde" |
| 35 | +Output: "1a1b1c1d1e" |
| 36 | +``` |
| 37 | + |
| 38 | +**Example 2:** |
| 39 | + |
| 40 | +``` |
| 41 | +Input: word = "aaaaaaaaaaaaaabb" |
| 42 | +Output: "9a5a2b" |
| 43 | +``` |
| 44 | + |
| 45 | +### Constraints |
| 46 | + |
| 47 | +- `1 <= word.length <= 2 * 105` |
| 48 | +- `word` consists only of lowercase English letters. |
| 49 | + |
| 50 | +--- |
| 51 | + |
| 52 | +## Solution for String Compression Problem |
| 53 | + |
| 54 | +### Intuition and Approach |
| 55 | + |
| 56 | +The problem can be solved using a brute force approach or an optimized approach. The brute force approach directly iterates through the string and constructs the result, while the optimized approach efficiently handles consecutive characters. |
| 57 | + |
| 58 | +<Tabs> |
| 59 | +<tabItem value="Brute Force" label="Brute Force"> |
| 60 | + |
| 61 | +### Approach 1: Brute Force (Naive) |
| 62 | + |
| 63 | +The brute force approach iterates through each character of the string, counts consecutive characters up to 9, and appends the count followed by the character to the result string. |
| 64 | + |
| 65 | +#### Code in Different Languages |
| 66 | + |
| 67 | +<Tabs> |
| 68 | +<TabItem value="C++" label="C++" default> |
| 69 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 70 | + |
| 71 | +```cpp |
| 72 | +class Solution { |
| 73 | +public: |
| 74 | + string compressString(string word) { |
| 75 | + string comp; |
| 76 | + int i = 0; |
| 77 | + while (i < word.length()) { |
| 78 | + char c = word[i]; |
| 79 | + int count = 0; |
| 80 | + while (i < word.length() && word[i] == c && count < 9) { |
| 81 | + count++; |
| 82 | + i++; |
| 83 | + } |
| 84 | + comp += to_string(count) + c; |
| 85 | + } |
| 86 | + return comp; |
| 87 | + } |
| 88 | +}; |
| 89 | +``` |
| 90 | +
|
| 91 | +</TabItem> |
| 92 | +<TabItem value="Java" label="Java"> |
| 93 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 94 | +
|
| 95 | +```java |
| 96 | +class Solution { |
| 97 | + public String compressString(String word) { |
| 98 | + StringBuilder comp = new StringBuilder(); |
| 99 | + int i = 0; |
| 100 | + while (i < word.length()) { |
| 101 | + char c = word.charAt(i); |
| 102 | + int count = 0; |
| 103 | + while (i < word.length() && word.charAt(i) == c && count < 9) { |
| 104 | + count++; |
| 105 | + i++; |
| 106 | + } |
| 107 | + comp.append(count).append(c); |
| 108 | + } |
| 109 | + return comp.toString(); |
| 110 | + } |
| 111 | +} |
| 112 | +``` |
| 113 | + |
| 114 | +</TabItem> |
| 115 | +<TabItem value="Python" label="Python"> |
| 116 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 117 | + |
| 118 | +```python |
| 119 | +class Solution: |
| 120 | + def compressString(self, word: str) -> str: |
| 121 | + comp = [] |
| 122 | + i = 0 |
| 123 | + while i < len(word): |
| 124 | + c = word[i] |
| 125 | + count = 0 |
| 126 | + while i < len(word) and word[i] == c and count < 9: |
| 127 | + count += 1 |
| 128 | + i += 1 |
| 129 | + comp.append(f"{count}{c}") |
| 130 | + return ''.join(comp) |
| 131 | +``` |
| 132 | + |
| 133 | +</TabItem> |
| 134 | +</Tabs> |
| 135 | + |
| 136 | +#### Complexity Analysis |
| 137 | + |
| 138 | +- Time Complexity: $O(n)$ |
| 139 | +- Space Complexity: $O(n)$ |
| 140 | +- Where `n` is the length of `word`. |
| 141 | +- The time complexity is $O(n)$ because we iterate through the string once. |
| 142 | +- The space complexity is $O(n)$ because we store the result in a new string. |
| 143 | + |
| 144 | +</tabItem> |
| 145 | +<tabItem value="Optimized" label="Optimized"> |
| 146 | + |
| 147 | +### Approach 2: Optimized Approach |
| 148 | + |
| 149 | +The optimized approach is similar to the brute force but handles the prefix length more efficiently, ensuring it counts up to 9 characters in each iteration. |
| 150 | + |
| 151 | +#### Code in Different Languages |
| 152 | + |
| 153 | +<Tabs> |
| 154 | +<TabItem value="C++" label="C++" default> |
| 155 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 156 | + |
| 157 | +```cpp |
| 158 | +class Solution { |
| 159 | +public: |
| 160 | + string compressString(string word) { |
| 161 | + string comp; |
| 162 | + int i = 0; |
| 163 | + while (i < word.length()) { |
| 164 | + char c = word[i]; |
| 165 | + int count = 1; |
| 166 | + while (i + count < word.length() && word[i + count] == c && count < 9) { |
| 167 | + count++; |
| 168 | + } |
| 169 | + comp += to_string(count) + c; |
| 170 | + i += count; |
| 171 | + } |
| 172 | + return comp; |
| 173 | + } |
| 174 | +}; |
| 175 | +``` |
| 176 | +
|
| 177 | +</TabItem> |
| 178 | +<TabItem value="Java" label="Java"> |
| 179 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 180 | +
|
| 181 | +```java |
| 182 | +class Solution { |
| 183 | + public String compressString(String word) { |
| 184 | + StringBuilder comp = new StringBuilder(); |
| 185 | + int i = 0; |
| 186 | + while (i < word.length()) { |
| 187 | + char c = word.charAt(i); |
| 188 | + int count = 1; |
| 189 | + while (i + count < word.length() && word.charAt(i + count) == c && count < 9) { |
| 190 | + count++; |
| 191 | + } |
| 192 | + comp.append(count).append(c); |
| 193 | + i += count; |
| 194 | + } |
| 195 | + return comp.toString(); |
| 196 | + } |
| 197 | +} |
| 198 | +``` |
| 199 | + |
| 200 | +</TabItem> |
| 201 | +<TabItem value="Python" label="Python"> |
| 202 | +<SolutionAuthor name="@ImmidiSivani"/> |
| 203 | + |
| 204 | +```python |
| 205 | +class Solution: |
| 206 | + def compressString(self, word: str) -> str: |
| 207 | + comp = [] |
| 208 | + i = 0 |
| 209 | + while i < len(word): |
| 210 | + c = word[i] |
| 211 | + count = 1 |
| 212 | + while i + count < len(word) and word[i + count] == c and count < 9: |
| 213 | + count += 1 |
| 214 | + comp.append(f"{count}{c}") |
| 215 | + i += count |
| 216 | + return ''.join(comp) |
| 217 | +``` |
| 218 | + |
| 219 | +</TabItem> |
| 220 | +</Tabs> |
| 221 | + |
| 222 | +#### Complexity Analysis |
| 223 | + |
| 224 | +- Time Complexity: $O(n)$ |
| 225 | +- Space Complexity: $O(n)$ |
| 226 | +- Where `n` is the length of `word`. |
| 227 | +- The time complexity is $O(n)$ because we iterate through the string once. |
| 228 | +- The space complexity is $O(n)$ because we store the result in a new string. |
| 229 | + |
| 230 | +</tabItem> |
| 231 | +</Tabs> |
| 232 | + |
| 233 | +--- |
| 234 | + |
| 235 | +<h2>Authors:</h2> |
| 236 | + |
| 237 | +<div style={{display: 'flex', flexWrap: 'wrap', justifyContent: 'space-between', gap: '10px'}}> |
| 238 | +{['ImmidiSivani'].map(username => ( |
| 239 | + <Author key={username} username={username} /> |
| 240 | +))} |
| 241 | +</div> |
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