93.复原IP地址

function restoreIpAddresses(s: string): string[] {
    let result = [];
    let path = [];

    const backtracking = (startIndex: number) => {
        if (path.length > 4) {
            return;
        }

        if (path.length === 4 && startIndex === s.length) {
            result.push(path.join('.'));
            return;
        };

        for (let i = startIndex; i < s.length; i++) {
            const val = s.slice(startIndex, i + 1);
            if (isValid(val)) {
                path.push(val);
                backtracking(i + 1);
                path.pop();
            }
        }
    };

    const isValid = (str: string) => {
        let resBool: boolean = true;
        let tempVal: number = Number(str);

        if (
            str.length === 0 || isNaN(tempVal) ||
            tempVal > 255 || tempVal < 0 ||
            (str.length > 1 && str[0] === '0')
        ) {
            resBool = false;
        }
        return resBool;
    };

    backtracking(0);
    return result;
};

78. 子集

function subsets(nums: number[]): number[][] {
    let result = [];
    let path = [];

    const backtracking = (startIndex: number) => {
        result.push([...path]);
        for (let i = startIndex; i < nums.length; i++) {
            path.push(nums[i]);
            backtracking(i + 1);
            path.pop();
        }
    };

    backtracking(0);
    return result;
};

90. 子集 ii

function subsetsWithDup(nums: number[]): number[][] {
    let result = [];
    let path = [];

    nums.sort((a, b) => a - b);

    const backtracking = (startIndex: number) => {
        result.push([...path]);
        for (let i = startIndex; i < nums.length; i++) {
            if (i > startIndex && nums[i] === nums[i - 1]) {
                continue;
            }

            path.push(nums[i]);
            backtracking(i + 1);
            path.pop();
        }
    };

    backtracking(0);
    return result;
};