You are given a 0-indexed string s of even length n. The string consists of exactly n / 2 opening brackets '[' and n / 2 closing brackets ']'.
A string is called balanced if and only if:
AB, where both A and B are balanced strings, or[C], where C is a balanced string.You may swap the brackets at any two indices any number of times.
Return the minimum number of swaps to make s balanced.
Example 1:
Input: s = "][][" Output: 1 Explanation: You can make the string balanced by swapping index 0 with index 3. The resulting string is "[[]]".
Example 2:
Input: s = "]]][[[" Output: 2 Explanation: You can do the following to make the string balanced: - Swap index 0 with index 4. s = "[]][][". - Swap index 1 with index 5. s = "[[][]]". The resulting string is "[[][]]".
Example 3:
Input: s = "[]" Output: 0 Explanation: The string is already balanced.
Constraints:
n == s.length2 <= n <= 106n is even.s[i] is either '[' or ']'.'[' equals n / 2, and the number of closing brackets ']' equals n / 2.class Solution {
public int minSwaps(String s) {
int stackSize = 0;
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
// If character is opening bracket, increment the stack size.
if (ch == '[') stackSize++;
else {
// If the character is closing bracket, and we have an opening bracket, decrease
// the stack size.
if (stackSize > 0) stackSize--;
}
}
return (stackSize + 1) / 2;
}
}