输入n个整数，找出其中最小的K个数。例如输入4,5,1,6,2,7,3,8这8个数字，则最小的4个数字是1,2,3,4,。
partition、堆、红黑树
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| class Solution {
public:
void swap(vector<int> &input, const int a, const int b)
{
int temp = input[a];
input[a] = input[b];
input[b] = temp;
}
int partition(vector<int> &input, const int start, const int end)
{
if (input.size() == 0)
{
return 0;
}
else
{
const int mid_value = input[0];
int left = start;
int right = end;
while (left < right)
{
while (input[right] >= mid_value && left < right)
{
right--;
}
swap(input, right, left);
while (input[left] <= mid_value && left < right)
{
left++;
}
swap(input, right, left);
}
return left;
}
}
vector<int> GetLeastNumbers_Solution(vector<int> input, int k) {
if (k == 0 || k > input.size())
{
return vector<int>();
}
else
{
int current_k = -1;
while (current_k != k)
{
if (current_k < k)
{
current_k = partition(input, current_k + 1, input.size() - 1);
}
else
{
current_k = partition(input, 0, current_k - 1);
}
}
return vector<int>(input.begin(), input.begin() + current_k);
}
}
};
|