Leetcode:set Matrix Zeroes-zero all rows and columns containing 0 of the matrix

1. Title

Set matrix zeroes (The matrix contains 0 rows and columns all placed 0)

2. Address of the topic

https://leetcode.com/problems/set-matrix-zeroes/

3. Topic content

English: Given a m x n Matrix, if an element is 0, set it entire row and column to 0.

Chinese: Given a matrix of MXN, if one of the elements is 0, then the entire row or collation containing the element is set to 0

4. Method of solving Problems 1

Use the first and first columns to record whether a row or column should be set to 0, and then use two status bits to mark whether the first row and the first column should also be set to 0.

The Java code is as follows:

/** * @ function Description: leetcode 73 - set matrix zeroes * @ Developer: Tsybius2014  * @ Development Time: November 7, 2015  */public class Solution {         /**     *  given a matrix, there will be 0 rows and columns of all elements 0     *   @param  matrix     */    public void  Setzeroes (Int[][] matrix)  {                 if  (matrix == null | |  matrix.length == 0 | |  matrix[0].length == 0)  {             return;        }                 int m = matrix.length;         int n = matrix[0].length;                 boolean needFillFirstRow = false;         boolean needFillFirstColumn = false;                 //find the line number and column number that contains 0, in the first element of the row where the element is located          for  (int i = 0; i < m; i++)  {             for  (int j = 0; j  < n; j++)  {                 if  (matrix[i][j] == 0)  {                     if  (i == 0)   {                         //if the first element of a row is originally 0, record this                          needFillFirstRow = true;                      }                     if  (j == 0)  {                         //if the first element of a column is originally a 0, Record this point                          needFillFirstColumn = true;                     }                     matrix[i][0] = 0;                      matrix[0][j] = 0;                 }            }         }        //fills the rows by the first element's record          for  (int j = 1; j < n; j+ +)  {            if  (matrix[0][j] ==  0)  {                 for  (int i = 0; i < m; i++)  {                     matrix[i][j] = 0;                 }             }        }         //fills each column with the record of the first element         for  (int  i = 1; i < m; i++)  {             if  (matrix[i][0] == 0)  {                 for  (int j = 1; j  < n; j++)  {                     matrix[i][j] = 0;                 }            }         }        //confirm if you need to fill the first line          if  (Needfillfirstrow)  {             for  (int j = 0; j < n; j+ +)  {                 matrix[0][j] = 0;            }         }        //confirm if you need to populate the first column          if  (Needfillfirstcolumn)  {             for  (int i = 0; i < m; i++)  {                 matrix[i][0] = 0;             }         }    }}

5. Method of solving Problems 2

Another way is to not use elements inside the matrix to record these changes. Instead, use the list (LinkedList) or hash set (HashSet) to record those rows and columns that need to be placed 0.

Java code using LinkedList is as follows:

import java.util.linkedlist;/** * @ function Description:leetcode 73 - set matrix  zeroes * @ Developer: tsybius2014 * @ Development Date: November 7, 2015  */public class Solution  {        /**     *  given a matrix, there will be 0 rows and columns of all elements placed 0      *  @param  matrix     */     public void setzeroes (Int[][] matrix)  {                 if  (matrix == null | |  matrix.length == 0 | |  matrix[0].length == 0)  {             return;        }                 //linked list for storing line numbers and column numbers         &nBsp Linkedlist<integer> linkedlistrows = new linkedlist<integer> ();         LinkedList<Integer> linkedListColumns = new  Linkedlist<integer> ();                 int m = matrix.length;        int  n = matrix[0].length;                 //find the line number and column number containing 0         for  (int i  = 0; i < m; i++)  {             for  (int j = 0; j < n; j++)  {                 if  (matrix[i][j ] == 0)  {                     Linkedlistrows.add (i);                     linkedlistcolumns.add (j);                 }             }        }                 //will contain 0 of each row of the 0        for   (int i : linkedlistrows)  {             for  (int num = 0; num < n; num++)  {                 matrix[i][num]  = 0;            }        }                 //will contain 0 of each column 0         for  (int j : linkedlistcolumns)  {             for  (int num = 0;  num < m; num++)  {                 matrix[num][j] = 0;             }        }    }}

The Java code for

Using HashSet is as follows:

import java.util.hashset;/** * @ function Description: leetcode 73 - set matrix zeroes  * @ Developer: tsybius2014 * @ Development Date: November 7, 2015  */public class solution {         /**     *  given a matrix, there will be 0 rows and columns of all elements placed 0      *  @param  matrix     */     public void setzeroes (Int[][] matrix)  {                 if  (matrix == null | |  matrix.length == 0 | |  matrix[0].length == 0)  {             return;        }                 //linked list for storing line numbers and column numbers           Hashset<integer> hashsetrows = new hashset<integer> ();         HashSet<Integer> hashSetColumns = new HashSet<Integer> ();                 int m  = matrix.length;        int n = matrix[0]. length;                // Find the line number and column number containing 0         for  (int i = 0; i  < m; i++)  {            for  (int j = 0; j < n; j++)  {                 if  (matrix[i][j] == 0)  {      &nBsp;              hashsetrows.add (i);                      hashsetcolumns.add (j);                 }            }         }                 //will contain 0 of each row 0        for  (int i :  hashsetrows)  {            for  (int  num = 0; num < n; num++)  {                 matrix[i][num] = 0;             }        }                 //will contain 0 of each column placed 0         for  (int j : hashsetcolumns)  {             for  (int num = 0; num < m; num+ +)  {                 matrix[num][j] = 0;            }         }    }}

END

Leetcode:set Matrix Zeroes-zero all rows and columns containing 0 of the matrix