Solution.ts

function maxPartitionsAfterOperations(s: string, k: number): number {
    const n = s.length;
    const f: Map<bigint, number> = new Map();
    const dfs = (i: number, cur: number, t: number): number => {
        if (i >= n) {
            return 1;
        }
        const key = (BigInt(i) << 27n) | (BigInt(cur) << 1n) | BigInt(t);
        if (f.has(key)) {
            return f.get(key)!;
        }
        const v = 1 << (s.charCodeAt(i) - 97);
        let nxt = cur | v;
        let ans = 0;
        if (bitCount(nxt) > k) {
            ans = dfs(i + 1, v, t) + 1;
        } else {
            ans = dfs(i + 1, nxt, t);
        }
        if (t) {
            for (let j = 0; j < 26; ++j) {
                nxt = cur | (1 << j);
                if (bitCount(nxt) > k) {
                    ans = Math.max(ans, dfs(i + 1, 1 << j, 0) + 1);
                } else {
                    ans = Math.max(ans, dfs(i + 1, nxt, 0));
                }
            }
        }
        f.set(key, ans);
        return ans;
    };
    return dfs(0, 0, 1);
}

function bitCount(i: number): number {
    i = i - ((i >>> 1) & 0x55555555);
    i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
    i = (i + (i >>> 4)) & 0x0f0f0f0f;
    i = i + (i >>> 8);
    i = i + (i >>> 16);
    return i & 0x3f;
}