Cattle-off wins the offer (constantly updated ~)

The first question: to find a two-dimensional array

Title Description

(The length of each one-dimensional array of same), each row from left to right in order of ascending sort, to sort each column in a two-dimensional array in order of increasing from top to bottom. A complete function, enter such a two-dimensional array and an integer, it is determined whether the array contains the integer.

 

Problem solution :

Due to the number of two-dimensional array is incremented from left to right, top to bottom increments, then we can consider the look from the bottom left corner, if val is greater than the array [i] [j], then, j ++, if less than a [i] [j] then, i--, otherwise the output true representation found val;

If in the end are not found, indicating that the element does not exist, returns false: that there is no the element.

 

Reference Code:

. 1  class Solution {
 2  public :
 . 3    BOOL the Find ( int target, Vector <Vector < int >> Array) {
 . 4      // Array is a two-dimensional array, where the empty judgment do not operate 
. 5      int rows = array.size ();
 . 6      int cols = array [ 0 ] .size ();
 . 7      int I = rows- . 1 , J = 0 ; // bottom left coordinates of elements 
. 8      the while (I> = 0 && J <cols) { // so as not to exceed the array range 
. 9        IF (target < Array [I] [J])
10          i--; // fewer elements to find, looking up 
. 11        the else  IF (target> Array [I] [J])
 12 is          J ++; // Find the larger elements, to find the right 
13 is        the else 
14          return  to true ; / / found 
15      }
 16      return  to false ;
 . 17    }
 18 is };

C++

 

The second question: replace spaces

Title Description

Please implement a function, a string to replace each space to "20%." For example, when the string is We Are Happy. After the string is replaced after We% 20Are% 20Happy.

 

Solution: Let's count up the number of spaces to calculate the length of the string after the replacement, and can be replaced from the back.

 

Reference Code:

  View Code

1 public class Solution {
2     public String replaceSpace(StringBuffer str) {
3         return str.toString().replaceAll("\\s", "%20");
4     }
5 }

View Code

 

Third question: print characters from the tail to the head

Title Description

Enter a list, by returning a list sequentially from the tail to the head of ArrayList.

 Solution: each head portion is inserted into the vector until the head == NULL;

 Reference Code:

 1 /**
 2 *  struct ListNode {
 3 *        int val;
 4 *        struct ListNode *next;
 5 *        ListNode(int x) :
 6 *              val(x), next(NULL) {
 7 *        }
 8 *  };
 9 */
10 class Solution {
11 public:
12     vector<int> printListFromTailToHead(ListNode* head) 
13     {
14         vector<int> ans;
15         while(head!=NULL)
16         {
17             ans.insert(ans.begin(),head->val);
18             head=head->next;
19         }
20         return ans;
21         
22     }
23 };

C++

 

 

 

 

 

 

 

Solution: Let's count up the number of spaces to calculate the length of the string after the replacement, and can be replaced from the back.

 

Reference Code:

  View Code

1 public class Solution {
2     public String replaceSpace(StringBuffer str) {
3         return str.toString().replaceAll("\\s", "%20");
4     }
5 }

View Code

 

Third question: print characters from the tail to the head

Title Description

Enter a list, by returning a list sequentially from the tail to the head of ArrayList.

 Solution: each head portion is inserted into the vector until the head == NULL;

 Reference Code:

 1 /**
 2 *  struct ListNode {
 3 *        int val;
 4 *        struct ListNode *next;
 5 *        ListNode(int x) :
 6 *              val(x), next(NULL) {
 7 *        }
 8 *  };
 9 */
10 class Solution {
11 public:
12     vector<int> printListFromTailToHead(ListNode* head) 
13     {
14         vector<int> ans;
15         while(head!=NULL)
16         {
17             ans.insert(ans.begin(),head->val);
18             head=head->next;
19         }
20         return ans;
21         
22     }
23 };

C++