leetcode

Author: ayoubzulfiqar

BuddyStrings/buddy_strings.dart

@@ -0,0 +1,112 @@
+/*
+
+
+-* 859. Buddy Strings *-
+
+
+
+Given two strings s and goal, return true if you can swap two letters in s so the result is equal to goal, otherwise, return false.
+
+Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at s[i] and s[j].
+
+For example, swapping at indices 0 and 2 in "abcd" results in "cbad".
+ 
+
+Example 1:
+
+Input: s = "ab", goal = "ba"
+Output: true
+Explanation: You can swap s[0] = 'a' and s[1] = 'b' to get "ba", which is equal to goal.
+Example 2:
+
+Input: s = "ab", goal = "ab"
+Output: false
+Explanation: The only letters you can swap are s[0] = 'a' and s[1] = 'b', which results in "ba" != goal.
+Example 3:
+
+Input: s = "aa", goal = "aa"
+Output: true
+Explanation: You can swap s[0] = 'a' and s[1] = 'a' to get "aa", which is equal to goal.
+ 
+
+Constraints:
+
+1 <= s.length, goal.length <= 2 * 104
+s and goal consist of lowercase letters.
+
+
+
+*/
+
+import 'dart:collection';
+
+class A {
+  bool buddyStrings(String s, String goal) {
+    if (s.length != goal.length) return false;
+
+    if (s == goal) {
+      List<int> count = List.filled(26, 0);
+
+      for (int i = 0; i < s.length; i++) {
+        int c = s.codeUnitAt(i) - 'a'.codeUnitAt(0);
+        count[c]++;
+        if (count[c] == 2) return true;
+      }
+
+      return false;
+    }
+
+    int index1 = -1;
+    int index2 = -1;
+
+    for (int i = 0; i < s.length; i++) {
+      if (s[i] != goal[i]) {
+        if (index1 == -1)
+          index1 = i;
+        else if (index2 == -1)
+          index2 = i;
+        else
+          return false;
+      }
+    }
+
+    if (index2 == -1) return false;
+
+    return (s[index1] == goal[index2] && s[index2] == goal[index1]);
+  }
+}
+
+class B {
+  bool buddyStrings(String s, String goal) {
+    final int n = s.length;
+
+    if (s == goal) {
+      final HashSet<String> temp = HashSet<String>();
+      for (int i = 0; i < s.length; i++) {
+        temp.add(s[i]);
+      }
+      return temp.length < goal.length; // Swapping same characters
+    }
+
+    int i = 0;
+    int j = n - 1;
+
+    while (i < j && s[i] == goal[i]) {
+      i++;
+    }
+
+    while (j >= 0 && s[j] == goal[j]) {
+      j--;
+    }
+
+    if (i < j) {
+      final List<String> sArr = s.split('');
+      String temp = sArr[i];
+      sArr[i] = sArr[j];
+      sArr[j] = temp;
+      s = sArr.join('');
+    }
+
+    return s == goal;
+  }
+}

BuddyStrings/buddy_strings.go

@@ -0,0 +1,34 @@
+package main
+
+func buddyStrings(s string, goal string) bool {
+	n := len(s)
+
+	if s == goal {
+		temp := make(map[rune]bool)
+		for _, c := range s {
+			temp[c] = true
+		}
+		return len(temp) < len(goal) // Swapping same characters
+	}
+
+	i := 0
+	j := n - 1
+
+	for i < j && s[i] == goal[i] {
+		i++
+	}
+
+	for j >= 0 && s[j] == goal[j] {
+		j--
+	}
+
+	if i < j {
+		sArr := []rune(s)
+		temp := sArr[i]
+		sArr[i] = sArr[j]
+		sArr[j] = temp
+		s = string(sArr)
+	}
+
+	return s == goal
+}

BuddyStrings/buddy_strings.md

@@ -240,6 +240,7 @@ This repo contain leetcode solution using DART and GO programming language. Most
 - [**956.** Tallest Billboard](TallestBillboard/tallest_billboard.dart)
 - [**864.** Shortest Path to Get All Keys](ShortestPathToGetAllKeys/shortest_path_to_get_all_keys.dart)
 - [**1970.** Last Day Where You Can Still Cross](LastDayWhereYouCanStillCross/last_day_where_you_can_still_cross.dart)
+- [**859.** Buddy Strings](BuddyStrings/buddy_strings.dart)
 
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