Solution.ts

function generateParenthesis(n: number): string[] {
    function dfs(l, r, t) {
        if (l > n || r > n || l < r) {
            return;
        }
        if (l == n && r == n) {
            ans.push(t);
            return;
        }
        dfs(l + 1, r, t + '(');
        dfs(l, r + 1, t + ')');
    }
    let ans = [];
    dfs(0, 0, '');
    return ans;
}