LeetCode[378] Kth Smallest Element in a Sorted Matrix

Given a n x n matrix where each of the rows and columns are sorted in ascending order, find the kth smallest element in the matrix.

Note that it is the kth smallest element in the sorted order, not the kth distinct element.

Example:

matrix = [

[ 1, 5, 9],

[10, 11, 13],

[12, 13, 15]

],

k = 8,

return 13.

Note:

You may assume k is always valid, 1 ≤ k ≤ n2.

建一个大小为k的priority_queue，保存k个最小的元素，算子为（默认）less，保证队头元素最大。但这样好像和matrix没什么关系…

题目给定的函数参数matrix是引用形式，也没有用上…

class Solution {
public:
int kthSmallest(vector<vector<int>>& matrix, int k) {
priority_queue<int> ssque;
for (int i = 0; i < k && i < matrix.size(); i++)
{
for (int j = 0; j < k / (i + 1) && j < matrix[i].size(); j++)
{
if (ssque.size() < k)
ssque.push(matrix[i][j]);
else
if (matrix[i][j] < ssque.top())
{
ssque.pop();
ssque.push(matrix[i][j]);
}
}
}
return ssque.top();
}
};