20140920 search for a two-dimensional matrix of Baidu pen questions

Question:

There is such a two-dimensional matrix A [n] [N], satisfying j <k, 1) A [I] [J] <A [I] [k]; 2) A [J] [I] <A [k] [I] (in fact, the data is decreased from the upper left corner to the lower right corner), given a number target, how to quickly search whether the two-dimensional coordinates are output in the matrix; otherwise, null is output. (assume that the data is not repeated)

For example

12  34  56  78  90  96

13  35  57  79  91  97

14  36  58  80  93  98

15  37  59  81  94  99

16  38  60  82  95  120

17  39  61  83  100  123

Search for 60 and output <4, 2>

Practice: traverse the matrix from the lower left corner, that is, make I = n-1, j = 0. If the value of (I, j) is greater than the search value, then I --, if it is small, J ++ is found. If it is equal, it is found.

Code:

void find(int array[][6], int n, int target){        int i = n - 1, j = 0;        while(i >= 0 && j < n)        {                if(array[i][j] == target)                {                        cout << '(' << i << ',' << j << ')' << endl;                        return;                }                else if(array[i][j] > target)                        i--;                else j++;        }                cout << "NULL\n";}

Result:

12
(0, 0)
34
(0, 1)
56
(0, 2)
78
(0, 3)
99
(3, 5)
123
(5, 5)
11
Null

20140920 search for a two-dimensional matrix of Baidu pen questions