思路
快排 + 双指针统计次数
比C++STL快一倍(150ms左右),STL大概在360ms左右
C++代码
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
const int N = 200010;
int n;
int q[N];
void quick_sort(int nums[], int l, int r)
{
if(l >= r) return ;
int x = nums[l + r >> 1], i = l - 1, j = r + 1;
while(i < j)
{
do i ++; while(nums[i] < x);
do j --; while(nums[j] > x);
if(i < j) swap(nums[i], nums[j]);
}
quick_sort(nums, l, j);
quick_sort(nums, j + 1, r);
}
int main()
{
scanf("%d", &n);
for(int i = 0; i < n; i ++) scanf("%d", &q[i]);
quick_sort(q, 0, n - 1);
for(int i = 0; i < n; i ++)
{
int j = i;
while(j < n && q[j] == q[i]) j ++;
printf("%d %d\n", q[i], j - i);
i = j - 1;
}
return 0;
}