标签:des style blog color io ar for art div
Question:
Given an M x N matrix in which each row and each column is sorted in ascending order, write a method to find an element.
1 package POJ; 2 3 public class Main { 4 5 /** 6 * 7 * 11.6 Given an M x N matrix in which each row and each column is sorted in 8 * ascending order, write a method to find an element. 9 * 10 */ 11 public static void main(String[] args) { 12 Main so = new Main(); 13 } 14 15 public static Coordinate findElement(int[][] matrix, int x) { 16 Coordinate origin = new Coordinate(0, 0); 17 Coordinate dest = new Coordinate(matrix.length - 1, 18 matrix[0].length - 1); 19 return findElement(matrix, origin, dest, x); 20 } 21 22 public static Coordinate findElement(int[][] matrix, Coordinate origin, 23 Coordinate dest, int x) { 24 if (!origin.inbounds(matrix) || !dest.inbounds(matrix)) { 25 return null; 26 } 27 if (matrix[origin.row][origin.column] == x) 28 return origin; 29 if (!origin.isBefore(dest)) 30 return null; 31 Coordinate start = (Coordinate) origin.clone(); 32 int diagDist = Math.min(dest.row - origin.row, dest.column 33 - origin.column); 34 Coordinate end = new Coordinate(start.row + diagDist, start.column 35 + diagDist); 36 Coordinate p = new Coordinate(0, 0); 37 38 while (start.isBefore(end)) { 39 p.setToAverage(start, end); 40 if (x > matrix[p.row][p.column]) { 41 start.row = p.row + 1; 42 start.column = p.column + 1; 43 } else { 44 end.row = p.row - 1; 45 end.column = p.column - 1; 46 } 47 } 48 return partitionAndSearch(matrix, origin, dest, start, x); 49 } 50 51 private static Coordinate partitionAndSearch(int[][] matrix, 52 Coordinate origin, Coordinate dest, Coordinate pivot, int elem) { 53 // TODO Auto-generated method stub 54 Coordinate lowerLeftOrigin = new Coordinate(pivot.row, origin.column); 55 Coordinate lowerLeftDest = new Coordinate(dest.row, pivot.column - 1); 56 Coordinate upperRightOrigin = new Coordinate(origin.row, pivot.column); 57 Coordinate upperRightDest = new Coordinate(pivot.row - 1, dest.column); 58 Coordinate lowerLeft = findElement(matrix, lowerLeftOrigin, 59 lowerLeftDest, elem); 60 if (lowerLeft == null) 61 return findElement(matrix, upperRightOrigin, upperRightDest, elem); 62 return lowerLeft; 63 } 64 } 65 66 class Coordinate implements Cloneable { 67 int row; 68 int column; 69 70 public Coordinate(int r, int c) { 71 row = r; 72 column = c; 73 } 74 75 public boolean inbounds(int[][] matrix) { 76 return row >= 0 && column >= 0 && row < matrix.length 77 && column < matrix[0].length; 78 } 79 80 public boolean isBefore(Coordinate p) { 81 return row <= p.row && column <= p.column; 82 } 83 84 public Object clone() { 85 return new Coordinate(row, column); 86 } 87 88 public void setToAverage(Coordinate min, Coordinate max) { 89 row = (min.row + max.row) / 2; 90 column = (min.column + max.column) / 2; 91 } 92 }
标签:des style blog color io ar for art div
原文地址:http://www.cnblogs.com/Phoebe815/p/3948490.html