[ 백준 BOJ ] 30804번 - 과일 탕후루 (C++)

https://www.acmicpc.net/problem/30804

 

 

생각 흐름

• 앞, 뒤로 빼는 점에서 투 포인터가 떠올랐다.

 

 

#include <iostream>
#include <memory.h>
#include <numeric>

#define endl '\n'

using namespace std;

int N;
int S[200000];

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    
    cin>>N;
    for(int i = 0; i<N; i++){
        cin>>S[i];
    }
    
    int maxNum=0;
    int countKind=0;
    int checked[10];
    memset(checked, 0, sizeof(checked));
    
    int i = 0, j = 1;
    if(S[i]==S[j]){
        countKind = 1;
        checked[S[i]]+=2;
    }else{
        countKind = 2;
        checked[S[i]]++;
        checked[S[j]]++;
    }
    
    if(N==1){
        cout<<1<<endl;
        return 0;
    }
    
    while(true){
        if(countKind<=2){
            if(j==N-1){
                break;
            }else{
                j++;
                if(++checked[S[j]]==1){
                    countKind++;
                }
            }
        }else{
            if(--checked[S[i]]==0){
                countKind--;
            }
            i++;
        }
        if(countKind<=2){
            maxNum = max(maxNum, accumulate(checked, checked+10, 0));
        }
    }
    
    cout<<maxNum<<endl;
    
    return 0;
}