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class Solution {
    public int[][] generateMatrix(int n) {
        int loop = 0; 
        int[][] res = new int[n][n];
        int start = 0; 
        int count = 1; 
        int i, j;
        while(loop < n / 2) {
             loop++;
            for (j = start; j < n - loop; j++) {
                res[start][j] = count++;
            }

            for (i = start; i < n - loop; i++) {
                res[i][j] = count++;
            }

            for (; j >= loop; j--) {
                res[i][j] = count++;
            }

            for (; i >= loop; i--) {
                res[i][j] = count++;
            }
           
            start++;
        }
        if (n % 2 == 1) {
           res[start][start] = count;
        }
        return res;
    }
}