balance parenthesis

Author: sachuverma

DSA Crack Sheet/README.md

@@ -82,6 +82,7 @@
 - [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/ "view question") - [Cpp Solution](./solutions/Longest%20Common%20Prefix.cpp)
 - [Min Number of Flips](https://practice.geeksforgeeks.org/problems/min-number-of-flips/0# "view question") - [Cpp Solution](./solutions/Min%20Number%20of%20Flips.cpp)
 - [Second most repeated string in a sequence](https://practice.geeksforgeeks.org/problems/second-most-repeated-string-in-a-sequence0534/1# "view question") - [Cpp Solution](./solutions/Second%20most%20repeated%20string%20in%20a%20sequence.cpp)
+- [Minimum Swaps for Bracket Balancing](https://practice.geeksforgeeks.org/problems/minimum-swaps-for-bracket-balancing/0# "view question") - [Cpp Solution](./solutions/Minimum%20Swaps%20for%20Bracket%20Balancing.cpp)
 - []( "view question") - [Cpp Solution](./solutions/.cpp)
 
 ### Searching & Sorting

DSA Crack Sheet/solutions/Minimum Swaps for Bracket Balancing.cpp

@@ -0,0 +1,77 @@
+/*
+Minimum Swaps for Bracket Balancing
+===================================
+
+You are given a string of 2N characters consisting of N ‘[‘ brackets and N ‘]’ brackets. A string is considered balanced if it can be represented in the for S2[S1] where S1 and S2 are balanced strings. We can make an unbalanced string balanced by swapping adjacent characters. Calculate the minimum number of swaps necessary to make a string balanced.
+
+Input:
+The first line of input contains an integer T denoting the number of test cases. Then T test cases follow. The first line of each test case contains an integer N denoting the length of the string.
+
+The second line of each test case contains the string consisting of '[' and ']'.
+
+Output:
+Print the minimum number of swaps to make the string balanced for each test case in a new line.
+
+Constraints:
+1<= T <=100
+1<= N <=100000
+
+Example:
+
+Input  : []][][
+Output : 2
+First swap: Position 3 and 4
+[][]][
+Second swap: Position 5 and 6
+[][][]
+
+Input  : [[][]]
+Output : 0
+String is already balanced.
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+  int t;
+  cin >> t;
+  while (t--)
+  {
+    int n;
+    cin >> n;
+    string s;
+    cin >> s;
+
+    vector<int> pos;
+    for (int i = 0; i < s.length(); ++i)
+      if (s[i] == '[')
+        pos.push_back(i);
+
+    int count = 0;
+    int p = 0;
+    long sum = 0;
+
+    for (int i = 0; i < s.length(); ++i)
+    {
+      if (s[i] == '[')
+      {
+        ++count;
+        ++p;
+      }
+      else if (s[i] == ']')
+        --count;
+
+      if (count < 0)
+      {
+        sum += pos[p] - i;
+        swap(s[i], s[pos[p]]);
+        ++p;
+        count = 1;
+      }
+    }
+    cout << sum << endl;
+  }
+  return 0;
+}