35 lines
858 B
C
35 lines
858 B
C
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int validate(const char *key) {
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int magic = 3;
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int count = 0;
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for (char c; (c = *key); key++) {
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if (c < '0' || c > '9') continue;
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int v = c - '0';
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if (++count == 13) {
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// final character.
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return magic % 10 == v;
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} else {
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v ^= magic * 2;
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magic += v;
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}
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}
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return 0;
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}
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int main(int argc, char **argv) {
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if (argc == 1) {
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// self-test.
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if (!validate("0000-00000-0003")) return -1;
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if (!validate("1234-56789-0123")) return -1;
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if (!validate("1337-42069-0008")) return -1;
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if (!validate("1998-00000-1997")) return -1;
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if (!validate("3333-33333-3333")) return -1;
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return 0;
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}
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int ret = 0;
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for (int i = 1; i < argc; i++) {
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if (!validate(argv[i])) ret++;
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}
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return ret;
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}
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