a+b=c a,b,c都是三位数且不重复

testabc.lua

local tostring = tostring
local tonumber = tonumber
local ssub = string.sub
local sformat = string.format
local tconcat = table.concat
local tinsert = table.insert

local si={1,2,3,4,5,6,7,8,9}
function printsi(si)
    print(tconcat(si))
end
local st = {}

function permutation(si,k,m)
    local i,j
    if k==m then
        local tmp = {si[1],si[2],si[3],si[4],si[5],si[6],si[7],si[8],si[9]}
        tinsert(st,tmp)
    else
        for j=k,m do
            si[j],si[k] = si[k],si[j]
            permutation(si,k+1,m)
            si[j],si[k] = si[k],si[j]
        end
    end
end
permutation(si,1,9)
--for _,si in pairs(st) do
--    printsi(si)
--end
local ta = {}
local count = 0
for _,si in pairs(st) do
    local a = si[1]*100+si[2]*10+si[3]
    local b = si[4]*100+si[5]*10+si[6]
    local c = si[7]*100+si[8]*10+si[9]
    --print(a,b,c)
    if a+b==c then
        if not ta[b] then
            ta[a] = true
            print(sformat("%d + %d = %d",a,b,c))
            count = count + 1
        end
    end
end
print("count:",count)

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