Solution.ts

function minimizeConcatenatedLength(words: string[]): number {
    const n = words.length;
    const f: number[][][] = Array(n)
        .fill(0)
        .map(() =>
            Array(26)
                .fill(0)
                .map(() => Array(26).fill(0)),
        );
    const dfs = (i: number, a: number, b: number): number => {
        if (i >= n) {
            return 0;
        }
        if (f[i][a][b] > 0) {
            return f[i][a][b];
        }
        const s = words[i];
        const m = s.length;
        const x =
            dfs(i + 1, a, s[m - 1].charCodeAt(0) - 97) - (s[0].charCodeAt(0) - 97 === b ? 1 : 0);
        const y =
            dfs(i + 1, s[0].charCodeAt(0) - 97, b) - (s[m - 1].charCodeAt(0) - 97 === a ? 1 : 0);
        return (f[i][a][b] = Math.min(x + m, y + m));
    };
    return (
        words[0].length +
        dfs(1, words[0][0].charCodeAt(0) - 97, words[0][words[0].length - 1].charCodeAt(0) - 97)
    );
}