Add Binary

Add Binary

@@ -0,0 +1,51 @@
+class Solution
+{
+public:
+    string addBinary(string a, string b)
+    {
+        int n1 = a.length();
+        int n2 = b.length();
+        int carry = 0;
+        string s = "";
+        while (n1 > 0 || n2 > 0)
+        {
+            int sum = 0;
+            if (n1 > 0)
+            {
+                sum += a[n1 - 1] - '0';
+                n1--;
+            }
+            if (n2 > 0)
+            {
+                sum += b[n2 - 1] - '0';
+                n2--;
+            }
+            sum += carry;
+            switch (sum)
+            {
+            case 0:
+                carry = 0;
+                s.push_back('0');
+                break;
+            case 1:
+                carry = 0;
+                s.push_back('1');
+                break;
+            case 2:
+                carry = 1;
+                s.push_back('0');
+                break;
+            case 3:
+                carry = 1;
+                s.push_back('1');
+                break;
+            }
+        }
+        if (carry != 0)
+        {
+            s.push_back('1');
+        }
+        reverse(s.begin(), s.end());
+        return s;
+    }
+};

Final Value of Variable After Performing Operations

@@ -0,0 +1,16 @@
+class Solution {
+public:
+int finalValueAfterOperations(vector& operations) {
+
+    int res = 0 ;
+
+    for( auto operation : operations ) {
+        if( operation[1] == '+' )
+            res++ ;
+        else
+            res-- ;
+    }
+
+    return res ;
+}
+};

Sort Characters By Frequency

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    string frequencySort(string s) {
+        unordered_map<char,int> mp;
+        for(int i= 0;i< s.length(); i++){
+            mp[s[i]]++;
+        }
+        priority_queue<pair<int,char>>pq;
+        for(auto i : mp){
+            pq.push({i.second,i.first});
+        }
+        string ans = "";
+        while(!pq.empty()){
+            pair<int,char> p = pq.top();
+            pq.pop();
+            while(p.first--){
+                ans+=p.second;
+            }
+        }
+        return ans;
+    }
+};