Data commit

Task/Modular-arithmetic/Lua/modular-arithmetic.lua

@@ -0,0 +1,61 @@
+function make(value, modulo)
+    local v = value % modulo
+    local tbl = {value=v, modulo=modulo}
+
+    local mt = {
+        __add = function(lhs, rhs)
+            if type(lhs) == "table" then
+                if type(rhs) == "table" then
+                    if lhs.modulo ~= rhs.modulo then
+                        error("Cannot add rings with different modulus")
+                    end
+                    return make(lhs.value + rhs.value, lhs.modulo)
+                else
+                    return make(lhs.value + rhs, lhs.modulo)
+                end
+            else
+                error("lhs is not a table in +")
+            end
+        end,
+        __mul = function(lhs, rhs)
+            if lhs.modulo ~= rhs.modulo then
+                error("Cannot multiply rings with different modulus")
+            end
+            return make(lhs.value * rhs.value, lhs.modulo)
+        end,
+        __pow = function(b,p)
+            if p<0 then
+                error("p must be zero or greater")
+            end
+
+            local pp = p
+            local pwr = make(1, b.modulo)
+            while pp > 0 do
+                pp = pp - 1
+                pwr = pwr * b
+            end
+            return pwr
+        end,
+        __concat = function(lhs, rhs)
+            if type(lhs) == "table" and type(rhs) == "string" then
+                return "ModInt("..lhs.value..", "..lhs.modulo..")"..rhs
+            elseif type(lhs) == "string" and type(rhs) == "table" then
+                return lhs.."ModInt("..rhs.value..", "..rhs.modulo..")"
+            else
+                return "todo"
+            end
+        end
+    }
+
+    setmetatable(tbl, mt)
+    return tbl
+end
+
+function func(x)
+    return x ^ 100 + x + 1
+end
+
+-- main
+local x = make(10, 13)
+local y = func(x)
+print("x ^ 100 + x + 1 for "..x.." is "..y)