059.Spiral Matrix II

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Solution 1: accepted

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public static int[][] generateMatrix(int n) {
	int[][] ret = new int[n][n];
	int left = 0,top = 0;
	int right = n -1,down = n - 1;
	int count = 1;
	while (left <= right) {
		for (int j = left; j <= right; j ++) {
			ret[top][j] = count++;
		}
		top ++;
		for (int i = top; i <= down; i ++) {
			ret[i][right] = count ++;
		}
		right --;
		for (int j = right; j >= left; j --) {
			ret[down][j] = count ++;
		}
		down --;
		for (int i = down; i >= top; i --) {
			ret[i][left] = count ++;
		}
		left ++;
	}
	return ret;
}