Leetcode Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates":
What if duplicates are allowed at most twice?

For example,
Given sorted array A =

[1,1,1,2,2,3]

,

Your function should return length =

5

, and A is now

[1,1,2,2,3]

.

典型的两指针问题

两个指针指向初始位置，一个指针i开始遍历，记录出现相同数的个数

如果遍历的指针i等于其前面的指针index且cnt个数超过两个，则继续移动遍历的指针

如果遍历的指针i等于其前面的指针index且cnt个数恰好为2，则更新index指针

如果遍历的指针不等于其前面的指针index，则出现相同的数，更新index指针，且清零计数器

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int removeDuplicates(int A[], int n){
if(n < 3) return n;
int index = 0, cnt = 0;
for(int i = 1; i < n; ++ i){
if(A[i] == A[index] && cnt < 2){
A[++index] = A[i];
cnt = 2;
}else if(A[i] != A[index]){
A[++index] = A[i];
cnt =0 ;
}
}
return index+1;
}

int main(){
int A[] = {1,1,1,2,2,3};
cout<<removeDuplicates(A,6)<<endl;
}