export default function distinctSubseqII(s: string): number {
    const MOD = 1000000007;
    const g: number[] = new Array(26).fill(0);
    const n = s.length;
    let total = 0;
    for (let i = 0; i < n; ++i) {
        const oi = s[i].charCodeAt(0) - "a".charCodeAt(0);
        const prev = g[oi];
        g[oi] = (total + 1) % MOD;
        total = (((total + g[oi] - prev) % MOD) + MOD) % MOD;
    }
    return total;
}