90 lines
1.3 KiB
Markdown
90 lines
1.3 KiB
Markdown
# Leetcode Ransom-Note
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#### 2022-06-14 13:19
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---
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##### Algorithms:
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#algorithm #hash_table
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##### Data structures:
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#DS #string #array
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##### Difficulty:
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#leetcode #coding_problems #difficulty_easy
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##### Related topics:
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##### Links:
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- [Link to problem](https://leetcode.com/problems/ransom-note/)
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***
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### Problem
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Given two strings `ransomNote` and `magazine`, return `true` _if_ `ransomNote` _can be constructed by using the letters from_ `magazine` _and_ `false` _otherwise_.
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Each letter in `magazine` can only be used once in `ransomNote`.
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#### Examples
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**Example 1:**
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```markdown
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**Input:** s = "leetcode"
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**Output:** 0
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```
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**Example 2:**
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```markdown
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**Input:** s = "loveleetcode"
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**Output:** 2
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```
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**Example 3:**
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```markdown
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**Input:** s = "aabb"
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**Output:** -1
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```
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#### Constraints
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**Constraints:**
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- `1 <= s.length <= 105`
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- `s` consists of only lowercase English letters.
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### Thoughts
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Super simple hash map, similar to [[Leetcode First-Unique-Character-In-a-String]]
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### Solution
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O(m + n)
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```cpp
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class Solution {
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public:
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bool canConstruct(string ransomNote, string magazine) {
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// hashmap, O(m + n)
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int hashMap[26] = {};
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for (char c : magazine) {
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hashMap[c - 'a']++;
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}
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for (char c : ransomNote) {
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if (hashMap[c - 'a']-- == 0)
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return false;
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}
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return true;
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}
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};
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```
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