SOURCE

let num = [2,3,5,7,9]
let result = []
let count = 0;

//js 求和版
const calc=(res)=>{
    for(let i = 0;i<num.length;i++){
        res.push(num[i]);
        let sum = res.reduce((preValue,curValue)=>preValue + curValue);
        if(sum===13){
            console.log("当前组合为",res);
            res.pop();
            count++;
            return
        }else if(sum < 13){
            calc(res)
        }
        res.pop();
    }

}



calc(result)
console.log(count)

//js 求差版
/*
const num = [2, 3, 5, 7, 9]
let count = 0;
const getCombination = (target, arr = [])=>{

    num.forEach(value => {
        if (target - value < 0) {
            return
        }else if (target - value === 0) {
            // console.log(arr.concat(value))
            console.log(arr.concat(value))
            count++;
            return
        }
        getCombination(target - value, arr.concat(value))
    })
}

getCombination(13)
console.log(count)



*/



//py版--https://www.v2ex.com/t/719057?p=1 中的#46楼
/*

num = [2,3,5,7,9]
result = []

count = 0;


def calc(result):
    for i in range(0,5):
        result.append(num[i])
        if sum(result) == 13:
            print(result)
            global count;
            count = count+1;
            result.pop()
            return
        elif sum(result) < 13:
            calc(result)
        result.pop()
    return


calc(result)
print(count)

*/