merge_lists_of_lists

merge_lists_of_lists.js

function process(result, val, temp_val) {
    var inner_val = isNaN(val) ? val : [val, val];
    
    if (temp_val.length == 0) { //no temp
        temp_val = inner_val;
    } else if ( (inner_val[1] -1) > temp_val[1] ) {  //flush temp
        if (temp_val[0] == temp_val[1]) {
            result.push(temp_val[0]);
        } else {
            result.push(temp_val[0] + '-' + temp_val[1]);
        }
        temp_val = inner_val;
    } else {
        temp_val[1] = inner_val[1];
    }
    return temp_val;
        
}


function isNumber(num) { return !isNaN(num) } 

function merge(left, right){
    var result = [],
        temp_val = [],
        il = 0,
        ir = 0;

    while (il < left.length && ir < right.length){
        var left_val = isNumber(left[il]) ? left[il]: left[il][0];
        var right_val = isNumber(right[ir]) ? right[ir] : right[ir][0];
        if (left_val < right_val){ //process left
            temp_val = process(result, left[il++], temp_val)
        } else { //process right
            temp_val = process(result, right[ir++], temp_val)
        }
    }
    
    var ls = left.slice(il);
    for(var b = 0; b < ls.length; b++) {
        temp_val = process(result, ls[b], temp_val)
    }
     var rs = right.slice(ir);
     for(var c = 0; c < rs.length; c++, temp_val) {
        temp_val = process(result, rc[c])

     }
     if (temp_val.length > 0) { 
        if (temp_val[0] == temp_val[1]) {
            result.push(temp_val[0]); 
        } else {
            result.push(temp_val[0] + '-' + temp_val[1]);
        }
     }

    return result;
}

var r = merge([[2,3],4,6,8,10,20], [3,[4,4],8,[13,14],16,18]).toString();

r

/*
2-4,6,8,10,13-14,16,18,20
*/