44 lines
991 B
Text
44 lines
991 B
Text
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/**
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* Computes longest common subsequence of two strings a and b.
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*/
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global buf = new int[]{0};
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string lcs(int i, int j, string a, string b) {
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if (i < 0 | j < 0) {
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return "";
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}
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var a_chars = array_of_string(a);
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var b_chars = array_of_string(b);
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var last_char_a = a_chars[i];
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var last_char_b = b_chars[j];
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if (last_char_a == last_char_b) {
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var prev_lcs = lcs(i - 1, j - 1, a, b);
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buf[0] = a_chars[i];
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var next_char = string_of_array(buf);
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return string_cat(prev_lcs, next_char);
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}
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var left_lcs = lcs(i, j - 1, a, b);
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var right_lcs = lcs(i - 1, j, a, b);
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var left_len = length_of_string(left_lcs);
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var right_len = length_of_string(right_lcs);
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if (left_len < right_len) {
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return right_lcs;
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} else {
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return left_lcs;
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}
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}
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int program(int argc, string[] argv) {
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var tomato = "TOMATO";
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var orating = "ORATING";
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print_string(lcs(5, 6, tomato, orating));
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return 0;
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}
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