Nearest Locker Distance

Practice on loops.

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public class NearestLockerDistance { static int[][] rotateMatrix(int[][] matrix) { int[][] result = new int[matrix[0].length][matrix.length]; for (int r = 0; r < matrix.length; r++) { for (int c = 0; c < matrix[0].length; c++) { result[c][r] = matrix[r][c]; } } return result; } static int[][] getLockerDistanceGrid(int cityLength, int cityWidth, int[] lockerXCoordinates, int[] lockerYCoordinates) { if (lockerXCoordinates == null || lockerYCoordinates == null || lockerXCoordinates.length != lockerYCoordinates.length) return null; int[][] city = new int[cityWidth][cityLength]; // initialize city to biggest numbers for (int i = 0; i < city[0].length; i++) // x for (int j = 0; j < city.length; j++) // y city[j][i] = Integer.MAX_VALUE; // mark the locker's distance. it also remembers the location of lockers for (int i = 0; i < lockerXCoordinates.length; i++) city[lockerYCoordinates[i] - 1][lockerXCoordinates[i] - 1] = 0; // calculate for each locker for (int i = 0; i < lockerXCoordinates.length; i++) { calcDistance(city, lockerYCoordinates[i], lockerXCoordinates[i]); } city = rotateMatrix(city); return city; } static void calcDistance(int[][] city, int y, int x) { y = y - 1; x = x - 1; // this is place can be optimized for (int i = 0; i < city[0].length; i++) // x for (int j = 0; j < city.length; j++)// y { if (city[j][i] != 0) { city[j][i] = Math.min(city[j][i], Math.abs(j - y) + Math.abs(i - x)); } } } }