The sword-finger offer algorithm Java implementation of find in two-dimensional arrays __ algorithm

The algorithm Java implementation of sword-finger offer

topic:

In a two-dimensional array, each row is sorted in ascending order from left to right , and each column is sorted in ascending order from top to bottom. Please complete a function, enter such a two-dimensional array and an integer to determine whether the array contains the function.

For example, the following two-dimensional array is each row, each column is an ascending sort. Returns True if the number 7 is found in this array, or FALSE if you look for an array of 5, because the array does not contain the number.

1 2 8 9

2 4 9 12

4 7 10 13

6 8 11 15

When we solve a problem, a very effective way is to start from a specific problem, through the analysis of simple concrete examples, try to find the general law.

Package com.ynu.www.offer;  public class Findfrommatrix {private static int[][] Sample = new int[][] {{1, 2, 8, 9}, {2, 4,  
  
    9, 12}, {4, 7, 10, 13}, {6, 8, 11, 15}}; public static void Printsample () {to (int i = 0; i < sample.length; i++) {for (int j = 0; j < Sample[i].length;  
            J + +) {System.out.print (Sample[i][j] + "");  
        } System.out.println (); } public static Boolean Getvaluefrommatrix (int[][] sample, int rows, int columns, int num)  
        {Boolean found = false;  
            if (sample!= null && rows > 0 && columns > 0) {int row = 0;  
            int column = Columns-1;  
                while (Row < rows && column >= 0) {int tempvalue = Sample[row][column];  
                if (num > Tempvalue) {++row; } ElSe if (num < tempvalue) {--column;  
                    else {found = true;  
                Break  
    }} return found;  
        public static void Main (string[] args) {printsample ();  
  
    System.out.println (Getvaluefrommatrix (Sample, 4, 4, 7)); }  
}

Based on the analysis, each time we pick the upper-right digits of the array lookup range, we can also select the lower-left digits, but we cannot select the upper-left or lower-right corners because we cannot narrow the lookup range.