add trick example of greatest-common-divisor, knuth-morris-pratt, primality-test, quick-pow, split-text

trick/knuth-morris-pratt.cpp

@@ -0,0 +1,29 @@
+#include <vector>
+#include <string>
+
+int knuth_morris_pratt(const std::string text, const std::string pattern) {
+	int n = text.length(), m = pattern.length();
+	std::vector<int> next(m, 0);
+	for (int i = 1, j = 0; i < m; i++) {
+		while (j > 0 && pattern[i] != pattern[j]) {
+			j = next[j - 1];
+		}
+		if (pattern[i] == pattern[j]) {
+			j++;
+		}
+		next[i] = j;
+	}
+
+	for (int i = 0, j = 0; i < n; i++) {
+		while (j > 0 && text[i] != pattern[j]) {
+			j = next[j - 1];
+		}
+		if (text[i] == pattern[j]) {
+			j++;
+		}
+		if (j == m) {
+			return i - m + 1;
+		}
+	}
+	return -1;
+}