Character Replacement to Match Strings

Problem Statement:
Given two strings s and t of the same length, determine whether it is possible to replace characters in s such that it becomes identical to t. Each character in s can be replaced with at most one unique character from t, and no two characters in s can map to the same character in t.

Approach

To solve this problem, we use two dictionaries (dic1 and dic2) to map characters from s to t and t to s respectively. These mappings help ensure one-to-one correspondence between characters.

Steps:

1. Initialize Variables:

   • Two dictionaries, dic1 and dic2, to track mappings.
   • A flag variable set to 1, indicating success.

2. Iterate Through Both Strings Simultaneously:

   • For each character pair (s[i], t[i]):
     • If s[i] is already in dic1 and maps to a different character than t[i], or if t[i] is in dic2 and maps to a different character than s[i], set flag = 0 and break.
     • Otherwise, add the mapping s[i] -> t[i] in dic1 and t[i] -> s[i] in dic2.

3. Final Check:

   • If flag is still 1 after processing all characters, return True.
   • Otherwise, return False.

Code Implementation

def canTransform(s, t):
    if len(s) != len(t):
        return False
    
    dic1 = {}
    dic2 = {}
    flag = 1
    
    for i in range(len(s)):
        if (s[i] in dic1 and dic1[s[i]] != t[i]) or (t[i] in dic2 and dic2[t[i]] != s[i]):
            flag = 0
            break
        dic1[s[i]] = t[i]
        dic2[t[i]] = s[i]
    
    return flag == 1
---

**Input:**  
`s = "abc", t = "def"`

**Execution:**  
- `dic1`: `{'a': 'd', 'b': 'e', 'c': 'f'}`  
- `dic2`: `{'d': 'a', 'e': 'b', 'f': 'c'}`  

**Output:**  
`True`

---

**Input:**  
`s = "foo", t = "bar"`

**Execution:**  
- Mapping `o -> a` is inconsistent.  

**Output:**  
`False`

---

**Input:**  
`s = "add", t = "egg"`

**Execution:**  
- `dic1`: `{'a': 'e', 'd': 'g'}`  
- `dic2`: `{'e': 'a', 'g': 'd'}`  

**Output:**  
`True`

---
**Input:**  
`s = "abc", t = "de"`

**Execution:**  
- Since the lengths are different, no transformation is possible.  

**Output:**  
`False`

---

**Input:**  
`s = "", t = ""`

**Execution:**  
- Both strings are empty, so they are trivially the same.  

**Output:**  
`True`