目录
一、题目描述
二、算法原理
2.1快速排序
2.2归并排序
三、代码实现
3.1快排代码实现
cpp
复制代码
class Solution {
public:
int getRandom(int left,int right,vector<int>& nums)
{
return nums[rand()%(right-left+1)+left];
}
void _sortArray(int left,int right,vector<int>& nums)
{
if(left>right)
{
return ;
}
int key=getRandom(left,right,nums);
int l=left-1,r=right+1,i=left;
while(i<r)
{
if(nums[i]<key)
swap(nums[++l],nums[i++]);
else if(nums[i]>key)
swap(nums[i],nums[--r]);
else
i++;
}
_sortArray(left,l,nums);
_sortArray(r,right,nums);
}
vector<int> sortArray(vector<int>& nums)
{
srand(time(NULL));
_sortArray(0,nums.size()-1,nums);
return nums;
}
};
3.2归并代码实现
cpp
复制代码
class Solution {
public:
void mergeSort(vector<int>& nums,int left,int right)
{
if(left>=right)
{
return;
}
int mid=left+(right-left)/2;
mergeSort(nums,left,mid);
mergeSort(nums,mid+1,right);
//合并两个有序数组
vector<int> v(right-left+1);
int cur1=left,cur2=mid+1,i=0;
while((cur1<=mid)&&(cur2<=right))
{
if(nums[cur1]<nums[cur2])
{
v[i++]=nums[cur1++];
}
else
{
v[i++]=nums[cur2++];
}
}
while(cur1<=mid) v[i++]=nums[cur1++];
while(cur2<=right) v[i++]=nums[cur2++];
//还原数组
for(int i=left;i<=right;i++)
{
nums[i]=v[i-left];
}
}
vector<int> sortArray(vector<int>& nums)
{
mergeSort(nums,0,nums.size()-1);
return nums;
}
};