lua里面求int数组的union,diff,inter,distinct 方法实现

--利用lua中的table是哈希表这一点进行计算
function lua_distinct_union (union_t1,union_t2)
    if(union_t2==nil) then
        union_t2={};
    end;
    local result={};
    for k,v in pairs(union_t1) do
        result[v]=v;
    end;
    for k,v in pairs(union_t2) do
        if result[v] ==nil then
            result[v]=v;
        end;
    end;
    union_t1=nil;
    union_t2=nil;
    return result;
end;

function lua_distinct (distinct_t)
    local result={};
    for k,v in pairs(distinct_t) do
        if(result[v]==nil) then
        result[v]=v;
    end;
end;
distinct_t=nil;
return result;
end;

function lua_distinct_diff(diff_t1,diff_t2) local result={};
    for k,v in pairs(diff_t1) do
        if(result[v]==nil) then
        result[v]=v;
    end;
end;

for k,v in pairs(diff_t2) do
    if(result[v]~=nil) then
    table.remove(result,v);
end;
end;
diff_t1=nil;
diff_t2=nil;
return result;
end;

function lua_distinct_inter (inter_t1,inter_t2)
    if inter_t1==nil and inter_t2~=nil then
        return lua_distinct(inter_t2);
    end;
    if inter_t1~=nil and inter_t2==nil then
        return lua_distinct(inter_t1);
    end;
    local temp1={};
    local temp2={};
    local result={};
    local num1=0;
    local num2=0;
    for k,v in pairs(inter_t1) do
        if(temp1[v]==nil) then
            temp1[v]=v;
            num1=num1+1;
        end;
    end;
    for k,v in pairs(inter_t2) do
        if(temp2[v]==nil) then
            temp2[v]=v;
            num2=num2+1;
        end;
    end;
    inter_t1=nil;
    inter_t2=nil;
    if num1<num2 then
        for k,v in pairs(temp1) do
            if temp2[k]~=nil then
                result[k]=temp1[k];
            end;
        end;
    else
        for k,v in pairs(temp2) do
            if temp2[k]~=nil then
                result[k]=temp1[k];
            end;
        end;
    end;
    temp1=nil;
    temp2=nil;
    return result;
end;


function lua_distinct_union_multiply(tablesneedunion)
    if(tablesneedunion==nil or #(tablesneedunion)==0) then
        error('lua_distinct_diff_Multiply传入参数为空');
    end;
    local result=tablesneedunion[1];
    if #(tablesneedunion)==1 then
        return lua_distinct_union(result,nil);
    end;
    for i=2,#(tablesneedunion) do
        local tmp=tablesneedunion[i];
        result=lua_distinct_union(tmp,result);
    end;
    tablesneedunion=nil;
    return result;
end;



function lua_distinct_inter_multiply(tablesneedinter)
    if(tablesneedinter==nil or #(tablesneedinter)==0) then
    error('lua_distinct_inter_multiply传入参数为空');
    end;
    local result=tablesneedinter[1];
    if #(tablesneedinter)==1 then
        return lua_distinct_inter(result,nil);
    end;
    for i=2,#(tablesneedinter) do
        local tmp=tablesneedinter[i];
        result=lua_distinct_inter(tmp,result);
        if  #(result)==0 then
            break;
        end;
    end;
    tablesneedinter=nil;
    return result;
end;

function getidsfromkeyvaluepair(keyvaluepair)
    local result={};
    if(keyvaluepair==nil) then
        return result;
    end;
    local num=1;
    for k,v in pairs(keyvaluepair) do
        result[num]=v;
        num=num+1;
    end;
    return result;
end;

function lua_getfinalids(structs)
    if #(structs)==1 then
        return getidsfromkeyvaluepair(temptable);
    end;
    local temptable=structs[1].temptable;
    for i=2,#(structs) do
        local tmp2=structs[i].temptable;
        if structs[i-1].flag==0 then
            temptable=lua_distinct_union(temptable,tmp2);
        else
            temptable=lua_distinct_inter(temptable,tmp2);
        end;
    end;
    return getidsfromkeyvaluepair(temptable);
end;


function lua_sortandtake(tableneedsort,takecount,isasc)
    if isasc==true then 
        table.sort(tableneedsort);
    else 
        table.sort(tableneedsort,function(a,b) return a>b end );
    end;    
    local result={};
    for i=0 ,takecount do
        result[i]=tableneedsort[i];    
    end;
    return result;
end;