Magic Squares In Grid LeetCode solution in Java

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class Solution {
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  public int numMagicSquaresInside(int[][] grid) {
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    int n = grid.length, m = grid[0].length, count = 0;
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    for (int i = 0; i < n - 2; i++) {
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      for (int j = 0; j < m - 2; j++) {
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        if (sum(i, j, grid)) count++;
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      }
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    }
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    return count;
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  }
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  public boolean sum(int x, int y, int[][] grid) {
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    int sum = grid[x][y] + grid[x][y + 1] + grid[x][y + 2], sum1 = 0, sum2 = 0;
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    int[] count = new int[10];
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    for (int i = 0; i < 3; i++) {
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      sum1 = 0;
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      sum2 = 0;
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      for (int j = 0; j < 3; j++) {
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        sum1 += grid[x + i][y + j];
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        sum2 += grid[x + j][y + i];
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        if (grid[x + i][y + j] < 1 || grid[x + i][y + j] > 9 || count[grid[x + i][y + j]] != 0)
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          return false;
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        count[grid[x + i][y + j]] = 1;
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      }
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      if (sum1 != sum || sum != sum2 || sum1 != sum2) {
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        return false;
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      }
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    }
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    sum1 = grid[x][y] + grid[x + 1][y + 1] + grid[x + 2][y + 2];
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    sum2 = grid[x][y + 2] + grid[x + 1][y + 1] + grid[x + 2][y];
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    if (sum1 != sum2 || sum1 != sum) {
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      return false;
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    }
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    return true;
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  }
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}