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export default function combinationSum(    candidates: number[],    target: number,): number[][] {    candidates.sort((a, b) => -b + a);    const ans: number[][] = [];    dfs(candidates, target, [], (path: number[]) => ans.push(path));    return ans;}
function dfs(    candidates: number[],    target: number,    path: number[],    output: (path: number[]) => void,) {    if (target === 0) {        output(path);        return;    }
    for (const [index, can] of candidates.entries()) {        if (target >= can) {            dfs(                index ? candidates.slice(index) : candidates,                target - can,                [...path, can],                output,            );        } else {            return;        }    }}