UPC: Difference between revisions

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@@ Line 719: / Line 719: @@
 : 7 0 6 4 6 6 7 4 3 0 3 Valid
 : 6 5 3 4 8 3 5 4 0 4 3 Valid</pre>
+=={{header|C++}}==
+{{trans|Kotlin}}
+<lang c++>#include <iostream>
+#include <locale>
+#include <map>
+#include <vector>
+std::string trim(const std::string &str) {
+    auto s = str;
+    //rtrim
+    auto it1 = std::find_if(s.rbegin(), s.rend(), [](char ch) { return !std::isspace<char>(ch, std::locale::classic()); });
+    s.erase(it1.base(), s.end());
+    //ltrim
+    auto it2 = std::find_if(s.begin(), s.end(), [](char ch) { return !std::isspace<char>(ch, std::locale::classic()); });
+    s.erase(s.begin(), it2);
+    return s;
+}
+template <typename T>
+std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {
+    auto it = v.cbegin();
+    auto end = v.cend();
+    os << '[';
+    if (it != end) {
+        os << *it;
+        it = std::next(it);
+    }
+    while (it != end) {
+        os << ", " << *it;
+        it = std::next(it);
+    }
+    return os << ']';
+}
+const std::map<std::string, int> LEFT_DIGITS = {
+    {"   ## #", 0},
+    {"  ##  #", 1},
+    {"  #  ##", 2},
+    {" #### #", 3},
+    {" #   ##", 4},
+    {" ##   #", 5},
+    {" # ####", 6},
+    {" ### ##", 7},
+    {" ## ###", 8},
+    {"   # ##", 9}
+};
+const std::map<std::string, int> RIGHT_DIGITS = {
+    {"###  # ", 0},
+    {"##  ## ", 1},
+    {"## ##  ", 2},
+    {"#    # ", 3},
+    {"# ###  ", 4},
+    {"#  ### ", 5},
+    {"# #    ", 6},
+    {"#   #  ", 7},
+    {"#  #   ", 8},
+    {"### #  ", 9}
+};
+const std::string END_SENTINEL = "# #";
+const std::string MID_SENTINEL = " # # ";
+void decodeUPC(const std::string &input) {
+    auto decode = [](const std::string &candidate) {
+        using OT = std::vector<int>;
+        OT output;
+        size_t pos = 0;
+        auto part = candidate.substr(pos, END_SENTINEL.length());
+        if (part == END_SENTINEL) {
+            pos += END_SENTINEL.length();
+        } else {
+            return std::make_pair(false, OT{});
+        }
+        for (size_t i = 0; i < 6; i++) {
+            part = candidate.substr(pos, 7);
+            pos += 7;
+            auto e = LEFT_DIGITS.find(part);
+            if (e != LEFT_DIGITS.end()) {
+                output.push_back(e->second);
+            } else {
+                return std::make_pair(false, output);
+            }
+        }
+        part = candidate.substr(pos, MID_SENTINEL.length());
+        if (part == MID_SENTINEL) {
+            pos += MID_SENTINEL.length();
+        } else {
+            return std::make_pair(false, OT{});
+        }
+        for (size_t i = 0; i < 6; i++) {
+            part = candidate.substr(pos, 7);
+            pos += 7;
+            auto e = RIGHT_DIGITS.find(part);
+            if (e != RIGHT_DIGITS.end()) {
+                output.push_back(e->second);
+            } else {
+                return std::make_pair(false, output);
+            }
+        }
+        part = candidate.substr(pos, END_SENTINEL.length());
+        if (part == END_SENTINEL) {
+            pos += END_SENTINEL.length();
+        } else {
+            return std::make_pair(false, OT{});
+        }
+        int sum = 0;
+        for (size_t i = 0; i < output.size(); i++) {
+            if (i % 2 == 0) {
+                sum += 3 * output[i];
+            } else {
+                sum += output[i];
+            }
+        }
+        return std::make_pair(sum % 10 == 0, output);
+    };
+    auto candidate = trim(input);
+    auto out = decode(candidate);
+    if (out.first) {
+        std::cout << out.second << '\n';
+    } else {
+        std::reverse(candidate.begin(), candidate.end());
+        out = decode(candidate);
+        if (out.first) {
+            std::cout << out.second << " Upside down\n";
+        } else if (out.second.size()) {
+            std::cout << "Invalid checksum\n";
+        } else {
+            std::cout << "Invalid digit(s)\n";
+        }
+    }
+}
+int main() {
+    std::vector<std::string> barcodes = {
+        "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
+        "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
+        "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
+        "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
+        "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
+        "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
+        "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
+        "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
+        "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
+        "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
+    };
+    for (auto &barcode : barcodes) {
+        decodeUPC(barcode);
+    }
+    return 0;
+}</lang>
+{{out}}
+<pre>[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
+[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
+[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
+[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
+Invalid digit(s)
+[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
+[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
+[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
+[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
+[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]</pre>
 =={{header|Factor}}==