feat: finish problem 76 related with minimum window substring

Author: bujosa

src/hard/minimum_window_substring.rs

@@ -1,6 +1,43 @@
 #![allow(dead_code)]
 pub fn min_window(s: String, t: String) -> String {
-    "".to_string()
+    if t.len() > s.len() {
+        return "".to_string();
+    }
+
+    let need_map = t.chars().fold([0; 128], |mut acc, c| {
+        acc[c as usize] += 1;
+        acc
+    });
+    let mut window_map = [0; 128];
+    let mut left = 0;
+    let mut right = 0;
+    let mut count = 0;
+    let mut min_substring = "".to_string();
+
+    while right < s.len() {
+        let c = s.chars().nth(right).unwrap();
+        window_map[c as usize] += 1;
+        if window_map[c as usize] <= need_map[c as usize] {
+            count += 1;
+        }
+
+        // If the window contains all the characters in t
+        // Try to shrink the window
+        while count == t.len() {
+            let c = s.chars().nth(left).unwrap();
+            if right - left + 1 < min_substring.len() || min_substring.is_empty() {
+                min_substring = s[left..=right].to_string();
+            }
+            window_map[c as usize] -= 1;
+            if window_map[c as usize] < need_map[c as usize] {
+                count -= 1;
+            }
+            left += 1;
+        }
+        right += 1;
+    }
+
+    min_substring
 }
 
 #[cfg(test)]
@@ -13,4 +50,18 @@ mod tests {
         let t = "ABC".to_string();
         assert_eq!(min_window(s, t), "BANC".to_string());
     }
+
+    #[test]
+    fn test_min_window_1() {
+        let s = "a".to_string();
+        let t = "aa".to_string();
+        assert_eq!(min_window(s, t), "".to_string());
+    }
+
+    #[test]
+    fn test_min_window_2() {
+        let s = "a".to_string();
+        let t = "a".to_string();
+        assert_eq!(min_window(s, t), "a".to_string());
+    }
 }

src/readme.md

@@ -56,5 +56,6 @@
   - [x] [739. Daily temperatures](../src/medium/daily_temperatures.rs)
   - [x] [853. Car fleet](../src/medium/car_fleet.rs)
 - [Hard](../src/hard)
-  - [x] [84. Largest rectangle in histogram](../src/hard/largest_rectangle_in_histogram.rs)
   - [x] [42. Trapping rain water](../src/hard/trapping_rain_water.rs)
+  - [x] [76. Minimum window substring](../src/hard/minimum_window_substring.rs)
+  - [x] [84. Largest rectangle in histogram](../src/hard/largest_rectangle_in_histogram.rs)

theory/categories/3.sliding_windows/readme.md

@@ -28,11 +28,11 @@
 - [x] [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | Medium | [Solution](../../../src/medium/longest_substring_without_repeating_characters.rs)
 - [x] [Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/) | Medium | [Solution](../../../src/medium/longest_repeating_character_replacement.rs)
 - [x] [Permutation in String](https://leetcode.com/problems/permutation-in-string/) | Medium | [Solution](../../../src/medium/permutation_in_string.rs)
-- [ ] [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/) | Hard | [Solution](../../../src/hard/minimum_window_substring.rs)
+- [x] [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/) | Hard | [Solution](../../../src/hard/minimum_window_substring.rs)
 - [ ] [Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/) | Hard | [Solution](../../../src/hard/sliding_window_maximum.rs)
 
 Category: `Sliding Windows`
 Created on: 2023-07-28 15:14:00
-Last modified on: 2023-08-10 21:05:00
+Last modified on: 2023-08-14 16:07:00
 Status: In Progress
 Author: [David Bujosa](https://github.com/bujosa)