Day10_LEETCODE_859. Buddy Strings.ipynb

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      "True\n"
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    "class Solution(object):\n",
    "    def buddyStrings(self, s, goal):\n",
    "        \"\"\"\n",
    "        :type s: str\n",
    "        :type goal: str\n",
    "        :rtype: bool\n",
    "        \"\"\"\n",
    "        # adding the constraint:\n",
    "        if len(s) > 2*(10**4) or len(goal) > 2*(10**4) or len(s) <1 or len(goal) <1 :  \n",
    "            return False\n",
    "\n",
    "        # s & goal cannot be same after swapping if length is not equal:\n",
    "        elif len(s) != len(goal):  \n",
    "            return False\n",
    "\n",
    "        # if length is equal, should have atleast 1 character that appears more than once\n",
    "        elif s == goal:\n",
    "            seen = set()\n",
    "            for char in s:\n",
    "                if char in seen: \n",
    "                    return True\n",
    "                seen.add(char)\n",
    "            return False\n",
    "\n",
    "        # cannot swap 2 characters if string length is 1\n",
    "        elif len(s)==1 or len(goal)==1:  \n",
    "            return False\n",
    "\n",
    "        # if string length is 2, reverse string and check if they are equal\n",
    "        elif len(s)==2 and len(goal)==2:\n",
    "            if s[::-1] == goal: \n",
    "                return True\n",
    "            else : \n",
    "                return False\n",
    "\n",
    "        # checking if there are only two indices where s and goal have different characters \n",
    "        # & if swapping characters at those 2 indices in s make s==goal\n",
    "        elif len(s)>2 and len(goal)>2:\n",
    "            diff=[]\n",
    "            for i in range(0,len(s)):\n",
    "                if s[i] != goal[i]:\n",
    "                    diff.append(i)\n",
    "            if len(diff) != 2:  \n",
    "                return False\n",
    "            elif len(diff) == 2 : \n",
    "                return s[diff[0]] == goal[diff[1]] and s[diff[1]] == goal[diff[0]]\n",
    "        \n",
    "        return False\n",
    "       \n",
    "solution = Solution()    \n",
    "result = solution.buddyStrings(\"ab\", \"ba\")\n",
    "print(result)"
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