Solved Single Number Problem in C++

LeetCode/Find Single Number/C++/Readme.md

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+# APPROACH 1: 
+# Time Complexity: O(N)
+# Space Complexity: O(N) => for unordered_map data structure
+This C++ function uses a unordered_map data structure to count the frequency of each element in the input vector 'nums'.
+It then iterates through the map to find the element with a frequency of 1,
+which corresponds to the single number that appears only once in the vector. The function returns this single number as the result.
+
+# APPROACH 2: 
+# Time Complexity: O(N)
+# Space Complexity: O(1)
+This C++ function uses the XOR (^) bitwise operation to find the single number in the 'nums' vector efficiently.
+It initializes 'result' to 0 and iterates through the vector, XORing each element with 'result.' 
+Since XORing the same number twice results in 0 (A ^ A = 0), and XORing any number with 0 results in the number itself (A ^ 0 = A),
+this process effectively cancels out all the duplicate numbers. Ultimately, 'result' will hold the value of the single number 
+that appears only once, and it returns this result as the answer.

LeetCode/Find Single Number/C++/Solution.cpp

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+// SOLUTION 1: 
+// Time Complexity: O(N)
+// Space Complexity: O(N)
+// Not an effiecient approach
+class Solution {
+public:
+    int singleNumber(vector<int>& nums) {
+        unordered_map<int,int>mp;
+        for(int i=0;i<nums.size();i++){
+            mp[nums[i]]++;
+        }
+        int res;
+        for(auto i:mp){
+            if(i.second==1){
+                res= i.first;
+            }
+        }
+        return res;
+    }
+};
+//SOLUTION 2:
+//Time Complexity: O(N)
+//Space Complexity: O(1)
+//Efficient approach
+class Solution {
+public:
+    int singleNumber(vector<int>& nums) {
+        int result=0;
+        for(int i=0;i<nums.size();i++)
+        {
+            result=result^nums[i];
+        }
+        return result;
+    }
+};