Finding in a two-dimensional array

Title Description

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

Idea One:

　　The two-dimensional array as a binary tree, the lower left corner of the tree is the midpoint, smaller than the target to go up, greater than target to the right. is actually a binary search tree.

Code implementation:

1  Public classSolution {2      Public BooleanFind (intTargetint[] Array) {3         if(Array = =NULL|| Array.Length = = 0| | Array[0] = =NULL|| Array[0].length = = 0){4             return false;5         }6         intLen = array.length-1;7         intLen2 = array[0].length-1;8         if(Array[0][0] >target)9             return false;Ten         if(Array[len][len2] <target) One             return false; A         inti =Len; -         intj = 0; -          while(I >= 0 && J <=len2) { the             if(Array[i][j] = =target) { -                 return true; -}Else if(Array[i][j] <target) { -J + +; +}Else{ -i--; +             } A         } at         return false; -          -     } -}

Idea two:

Using binary search, the matrix is regarded as the upper triangle and the lower triangle, and the two points are searched separately.

Code implementation:

  Public Static BooleanFind (int[] Array,inttarget) {        if(Array = =NULL|| Array.Length = = 0 | | Array[0] = =NULL|| Array[0].length = = 0){            return false; }        intLow,high,mid;  for(intj = 0; J < Array.Length; J + +) { low=J; High= Array.length-1; Mid= (low + high)/2;  while(Low <=High )                {System.out.println (array[mid][j]); if(Array[mid][j] = =target) {                    return true; }                if(Array[mid][j] >target) { High= Mid-1; }Else{ Low= Mid + 1; } Mid= (low + high)/2; }        }         for(inti = 0; i < array.length-1; i++) { low= i + 1; High= Array[i].length-1; Mid= (low + high)/2;  while(Low <=High )                {System.out.println (Array[i][mid]); if(Array[i][mid] = =target) {                    return true; }                if(Array[i][mid] >target) { High= Mid-1; }Else{ Low= Mid + 1; } Mid= (low + high)/2; }        }        return false; }

Sequential lookups are not recommended.

　　

Finding in a two-dimensional array