Codeforces 1129C Morse Code dp

Morse Code

Every time a character is added until a time when there have been no substring of statistics into the program, this can be used to check the dictionary tree appeared not.

#include<bits/stdc++.h>
#define LL long long
#define LD long double
#define ull unsigned long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ALL(x) (x).begin(), (x).end()
#define fio ios::sync_with_stdio(false); cin.tie(0);
 
using namespace std;
 
const int N = 3000 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;
const double PI = acos(-1);
 
template<class T, class S> inline void add(T &a, S b) {a += b; if(a >= mod) a -= mod;}
template<class T, class S> inline void sub(T &a, S b) {a -= b; if(a < 0) a += mod;}
template<class T, class S> inline bool chkmax(T &a, S b) {return a < b ? a = b, true : false;}
template<class T, class S> inline bool chkmin(T &a, S b) {return a > b ? a = b, true : false;}
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
int m, n;
int years;
int a [N];
int dp [N];
 
int all = 1 ;
int ch [N * N] [ 2 ];
 
bool check(int l, int r) {
    int x = a[l], y = a[l + 1], z = a[l + 2], w = a[l + 3];
    if(x == 0 && y == 0 && z == 1 && w == 1) return false;
    if(x == 0 && y == 1 && z == 0 && w == 1) return false;
    if(x == 1 && y == 1 && z == 1 && w == 0) return false;
    if(x == 1 && y == 1 && z == 1 && w == 1) return false;
    return true;
}
 
void calc(int n) {
    dp[n + 1] = 1;
    int u = 1;
    for(int i = n; i >= 1; i--) {
        dp[i] = 0;
        if(i + 1 <= n + 1) add(dp[i], dp[i + 1]);
        if(i + 2 <= n + 1) add(dp[i], dp[i + 2]);
        if(i + 3 <= n + 1) add(dp[i], dp[i + 3]);
        if(i + 4 <= n + 1 && check(i, i + 3)) add(dp[i], dp[i + 4]);
        if(!ch[u][a[i]]) {
            ch [u] [a [i]] = ++ tot;
            add(ans, dp[i]);
        }
        u = ch[u][a[i]];
    }
}
 
int main () {
    scanf("%d", &m);
    for(int i = 1; i <= m; i++) {
        scanf("%d", &a[i]);
    }
    for(int i = 1; i <= m; i++) {
        calc (i);
        printf("%d\n", ans);
    }
    return 0;
}
 
/*
*/