Excel Sheet Column Number LeetCode solution in Java

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class Solution {
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  public int titleToNumber(String columnTitle) {
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    int n = columnTitle.length();
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    int pow = 0;
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    int res = 0;
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    for (int i = n - 1; i >= 0; i--) {
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      char c = columnTitle.charAt(i);
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      res += (c - 64) * Math.pow(26, pow);
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      pow++;
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    }
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    return res;
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  }
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}