01 Matrix

DescriptionSubmissionsSolutions

• Total Accepted: 3068
• Total Submissions: 9208
• Difficulty: Medium
• Contributors:Stomach_ache

Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell.

The distance between two adjacent cells is 1.

Example 1: 
Input:

0 0 00 1 00 0 0

Output:

0 0 00 1 00 0 0

Example 2: 
Input:

0 0 00 1 01 1 1

Output:

0 0 00 1 01 2 1

Note:

1. The number of elements of the given matrix will not exceed 10,000.
2. There are at least one 0 in the given matrix.

1. The cells are adjacent in only four directions: up, down, left and right.

Java代码：

public class Solution {
    public List<List<Integer>> updateMatrix(List<List<Integer>> matrix) {
LinkedList<int[]> que=new LinkedList<int[]>();
for(int i=0;i<matrix.size();i++)
for(int j=0;j<matrix.get(0).size();j++){
if(matrix.get(i).get(j)==0)que.addLast(new  int[]{i,j});
else matrix.get(i).set(j,Integer.MAX_VALUE);
}
int[][] f={{1,0},{-1,0},{0,1},{0,-1}};
while(!que.isEmpty()){
int[] cur=que.pollFirst();
for(int[] ff:f){
int r=ff[0]+cur[0];
int c=ff[1]+cur[1];
if(r<0||r>=matrix.size()||c<0||c>=matrix.get(0).size()||matrix.get(r).get(c)<=matrix.get(cur[0]).get(cur[1])+1)continue;
   matrix.get(r).set(c,matrix.get(cur[0]).get(cur[1])+1);
que.addLast(new int[]{r,c});
}
}

return matrix;

}
}

时间复杂度：O（N*M）