bts16p3.cpp

// Ivan Carvalho
// Solution to https://dmoj.ca/problem/bts16p3
#include <cstdio>
#include <cstring>
#define MOD 1000000007
#define MAXN 100010
int dp[MAXN], resp, n, vetor[MAXN];
char entrada[MAXN];
inline int add(int x, int y) { return (x + y) % MOD; }
int solve(int pos) {
    if (dp[pos] != -1) return dp[pos];
    if (pos == n || vetor[pos + 1] != vetor[pos]) return dp[pos] = 1;
    return dp[pos] = add(1, solve(pos + 1));
}
int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%s", entrada);
        if ('a' <= entrada[0] && entrada[0] <= 'z') {
            vetor[i] = entrada[0] - 'A';
        } else {
            vetor[i] = entrada[0] - 'A';
        }
    }
    // for(int i=1;i<=n;i++) printf("%d ",vetor[i]);
    // printf("\n");
    memset(dp, -1, sizeof(dp));
    for (int i = 1; i <= n; i++) {
        resp = add(resp, solve(i));
    }
    printf("%d\n", resp);
    return 0;
}