leetcode 378. Kth Smallest Element in a Sorted Matrix 解题报告

原题链接

解题思路

解题代码

public class Solution {
public int kthSmallest(int[][] matrix, int k) {
PriorityQueue<Num> q = new PriorityQueue<>();
int n = matrix.length;
int count = 0;
int res = 0;
q.offer(new Num(0,0,matrix[0][0]));
boolean[][] visited = new boolean

;
visited[0][0] = true;
while(!q.isEmpty()) {
Num num = q.poll();
if(++count == k) {
return num.val;
}
if(num.x + 1 < n && !visited[num.x + 1][num.y]) {
Num tnum = new Num(num.x + 1,num.y,matrix[num.x + 1][num.y]);
q.offer(tnum);
visited[num.x + 1][num.y] = true;
}
if(num.y + 1 < n && !visited[num.x][num.y + 1]) {
Num tnum = new Num(num.x,num.y + 1,matrix[num.x][num.y + 1]);
q.offer(tnum);
visited[num.x][num.y + 1] = true;
}
}
return -1;
}
}
class Num implements Comparable<Num>{
int x;
int y;
int val;
Num(int x,int y,int val) {
this.x = x;
this.y = y;
this.val = val;
}
@Override
public int compareTo(Num o) {
return this.val - o.val;
}
}