day25打卡

3. 组合总和III

var combinationSum3 = function(k, n) {
    let temp = [];
    const ans = [];
    const check = (mask, k, n) => {
        temp = [];
        for (let i = 0; i < 9; ++i) {
            if ((1 << i) & mask) {
                temp.push(i + 1);
            }
        }
        return temp.length === k && temp.reduce((previous, value) => previous + value, 0) === n;
    }

    for (let mask = 0; mask < (1 << 9); ++mask) {
        if (check(mask, k, n)) {
            ans.push(temp);
        }
    }
    return ans;
};

4. 电话号码的字母组合

var combinationSum3 = function(k, n) {
    let temp = [];
    const ans = [];
    const check = (mask, k, n) => {
        temp = [];
        for (let i = 0; i < 9; ++i) {
            if ((1 << i) & mask) {
                temp.push(i + 1);
            }
        }
        return temp.length === k && temp.reduce((previous, value) => previous + value, 0) === n;
    }

    for (let mask = 0; mask < (1 << 9); ++mask) {
        if (check(mask, k, n)) {
            ans.push(temp);
        }
    }
    return ans;
};