Create Minimum_swaps_for_bracket_balancing

This is a greedy problem contribution.

Author: Op-panda

Greedy/Minimum_swaps_for_bracket_balancing

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+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+ 
+// Function to calculate swaps required
+long swapCount(string s)
+{
+    // Keep track of '['
+    vector<int> pos;
+    for (int i = 0; i < s.length(); ++i)
+        if (s[i] == '[')
+            pos.push_back(i);
+ 
+    int count = 0; // To count number of encountered '['
+    int p = 0;  // To track position of next '[' in pos
+    long sum = 0; // To store result
+ 
+    for (int i = 0; i < s.length(); ++i)
+    {
+        // Increment count and move p to next position
+        if (s[i] == '[')
+        {
+            ++count;
+            ++p;
+        }
+        else if (s[i] == ']')
+            --count;
+ 
+        // We have encountered an unbalanced part of string
+        if (count < 0)
+        {
+            // Increment sum by number of swaps required
+            // i.e. position of next '[' - current position
+            sum += pos[p] - i;
+            swap(s[i], s[pos[p]]);
+            ++p;
+ 
+            // Reset count to 1
+            count = 1;
+        }
+    }
+    return sum;
+}
+ 
+// Driver code
+int main()
+{
+    string s = "[]][][";
+    cout << swapCount(s) << "\n";
+ 
+    s = "[[][]]";
+    cout << swapCount(s) << "\n";
+    return 0;
+}