var threeSum = function(nums) {
    return calc(nums);
};


function compareNumbers(a, b) {
    return a - b;
}



const createMap = (nums) => {
    const map = new Map();
    let v = Infinity;
    for (let i = nums.length - 1; i >= 0 && v > 0; i--) {
        v = nums[i];
        if (!map.has(v)) map.set(v, i);
    }
    return map;
};

const calc = (nums) => {
    if (nums.length < 3)
        return [];
    nums.sort(compareNumbers);
    const map = createMap(nums);
    const result = [];
    let prevB = null;
    let prevA = -Infinity;
    for (let i = 0; i < nums.length - 2 && prevA <= 0; i++) {
        const a = nums[i];
        if (a !== prevA) {
            prevA = a;
            let bIndex = i + 1;
            while (bIndex < nums.length - 1) {
                const b = nums[bIndex];
                let c = Infinity;
                if (b !== prevB && b < c) {
                    prevB = b;
                    c = 0 - a - b;
                    const cIndex = map.get(c);
                    if (cIndex > bIndex)
                        result.push([a, b, c]);
                }
                bIndex++;
            }
        }
    }
    return result;
};