Submission #37396196

---

Source Code Expand

#include<bits/stdc++.h>
#define LL long long
#define MOD 998244353
using namespace std;
int inc(const int &a, const int &b)
{
    return a + b >= MOD ? a + b - MOD : a + b;
}
int dec(const int &a, const int &b)
{
    return a - b < 0 ? a - b + MOD : a - b;
}
void Inc(int &a, const int &b)
{
    ((a += b) >= MOD) && (a -= MOD);
}
const int N = 2e5 + 5;
int n, a[N], f[N], sum[N];
int cnt[N], num;
int main()
{
    scanf("%d", &n);
    for(int i = 1; i <= n; ++i)
        scanf("%d", &a[i]);
    f[0] = 1;
    int l = 1, r = 1;
    for(int i = 1; i <= n; ++i)
    {
        f[i] = f[i - 1];
        if(a[i] == a[i - 1])
            l = i;
        if(i > 2 && a[i] != a[i - 1] && a[i - 1] != a[i - 2])
            Inc(f[i], f[i - 2]);
        if(cnt[a[i]] == 0) num++;
        cnt[a[i]]++;
        while(r < i - 2 && num >= 3)
        {
            cnt[a[r]]--;
            if(!cnt[a[r]])
                --num;
            ++r;
        }
        if(l <= r) Inc(f[i], dec(sum[r - 1], sum[l - 1]));
        sum[i] = inc(sum[i - 1], f[i]);
    }
    printf("%d\n", f[n]);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:22:10: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   22 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
./Main.cpp:24:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   24 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~

Judge Result