From a97fdd289532ff500175b690c2a78de3ccb91331 Mon Sep 17 00:00:00 2001
From: Shine wOng <1551885@tongji.edu.cn>
Date: Wed, 21 Aug 2019 20:57:29 +0800
Subject: [PATCH] implement kmp algorithm, all tests passed.

---
 thu_dsa/chp11/kmp.cpp      | 28 ++++++++++++++++++++++++++++
 thu_dsa/chp11/kmp.h        |  7 +++++++
 thu_dsa/chp11/string.md    |  9 +++++++++
 thu_dsa/chp11/test_kmp.cpp | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+)
 create mode 100644 thu_dsa/chp11/kmp.cpp
 create mode 100644 thu_dsa/chp11/kmp.h
 create mode 100644 thu_dsa/chp11/string.md
 create mode 100644 thu_dsa/chp11/test_kmp.cpp

diff --git a/thu_dsa/chp11/kmp.cpp b/thu_dsa/chp11/kmp.cpp
new file mode 100644
index 0000000..a0f02f6
--- /dev/null
+++ b/thu_dsa/chp11/kmp.cpp
@@ -0,0 +1,28 @@
+#include "kmp.h"
+#include <iostream>
+
+int* makeNext(char* str){
+	int* next;
+	int len, i = 0, j = -1;
+	for (len = 0; str[len] != '\0'; ++len);
+	next = new int[len];
+	next[0] = -1;
+	while(i < len - 1){
+		if(j < 0 || str[i] == str[j]) next[++i] = ++j;
+		else						  j = next[j];
+	}
+	return next;
+}
+
+int match(char* text, char* pattern){
+	int* next = makeNext(pattern);
+	int i = 0, j = 0, m = strlen(text), n = strlen(pattern);
+	while(i < m && j < n){
+		if(j < 0 || text[i] == pattern[j]){
+			++i;
+			++j;
+		}
+		else j = next[j];
+	}
+	return i - j;
+}
diff --git a/thu_dsa/chp11/kmp.h b/thu_dsa/chp11/kmp.h
new file mode 100644
index 0000000..70cfeeb
--- /dev/null
+++ b/thu_dsa/chp11/kmp.h
@@ -0,0 +1,7 @@
+#ifndef KMP_H_
+#define KMP_H_
+
+int* makeNext(char* str);
+int  match(char* text, char* pattern);
+
+#endif
diff --git a/thu_dsa/chp11/string.md b/thu_dsa/chp11/string.md
new file mode 100644
index 0000000..1999815
--- /dev/null
+++ b/thu_dsa/chp11/string.md
@@ -0,0 +1,9 @@
+Conclusions on String
+====================
+
++ `串`的特点：串长要远远大于字母表的大小
+
+
+## KMP
+> 为什么要取最长自匹配？
+快速右移 + 避免回退。（怎么理解）
diff --git a/thu_dsa/chp11/test_kmp.cpp b/thu_dsa/chp11/test_kmp.cpp
new file mode 100644
index 0000000..1ad267f
--- /dev/null
+++ b/thu_dsa/chp11/test_kmp.cpp
@@ -0,0 +1,35 @@
+#include "kmp.h"
+#include <iostream>
+#include <cassert>
+
+using std::cout;
+using std::endl;
+
+void test_make_next(){
+	char* str = "chine chinchilla";
+	int exp[] = { -1, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 1, 2, 3, 0, 0 };
+	int* result = makeNext(str);
+	for (int ix = 0; ix != strlen(str); ++ix)
+		assert(exp[ix] == result[ix]);
+}
+
+void test_match(){
+	char* text = "chine chinchilla";
+	char* p1   = "chine";
+	char* p2   = "chinc";
+	char* p3   = "chinec";
+	assert(match(text, p1) == 0);
+	assert(match(text, p2) == 6);
+	assert(match(text, p3) == 16);
+}
+
+int main(){
+	cout << "begin tests..." << endl;
+
+	test_make_next();
+	test_match();
+
+	cout << "All tests passed." << endl;
+	system("pause");
+	return 0;
+}