数据结构串的应用，实验

于 2018-10-14 15:41:44 发布
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分类专栏： 数据结构
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本文链接：https://blog.youkuaiyun.com/Perce_Issac/article/details/82972384
版权 
#include<iostream>
#include<string.h>
using namespace std;
const int MAXNUM = 1000;
int main() {
	int t;
	cin >> t;
	char chars[MAXNUM];
	char chart[MAXNUM];
	while (t--) {
		memset(chars, 0, MAXNUM);
		memset(chart, 0, MAXNUM);
		char m;
		int n = 1;
		while (cin >> m) {
			chars[n] = m;
			n++;
		}
		int nums = n;
		n = 1;
		while (cin >> m) {
			chart[n] = m;
			n++;
		}
		int numt = n;


		
	}
}

哇太气人了，写到这里发现这道题要求用字符串，这真的难受

#include<iostream>
#include<string>
using namespace std;
class myString {
private:
	string mainstr;
	int size;
	void GetNext(string p, int next[]);
	int kmpFind(string p, int pos, int next[]);

public:
	myString();
	~myString();
	void SetVal(string sp);
	int kmpFindSubstr(string p, int pos);
 };

myString::myString() {
	size = 0;
	mainstr = "";
}
myString::~myString() {
	size = 0;
	mainstr = "";
}

void myString::SetVal(string sp) {
	mainstr = "";
	mainstr.assign(sp);//这什么
	size = mainstr.length();
}

int myString::kmpFindSubstr(string p, int pos) {
	int i;
	int L = p.length;
	int *next = new int[L];
	GetNext(p, next);
	for (int i = 0; i < L; i++) {
		cout << next[i];
	}
	cout << endl;
	int v = -1;
	v = kmpFind(p, pos, next);
	delete[] next;
	return v;
}

void myString::GetNext(string p, int next[]) {

}

int  myString::kmpFind(string p, int pos, int next[]) {

}

写到这里突然想，为什么非要用类来实现呢

 

自己应该学习一些大佬的代码风格，力求简洁明了快速

#include<iostream>
#include<string>
#include<string.h>
const int MAXN = 1000;
using namespace std;

void getNext(string p, string next);
int kmpFind(string p, string s, string next, int pos);


void getNext(string p, string next) {
	int i = 1;
	next[i] = 0;
	int j = 0;
	while (i < p[0]) {
		if (j == 0 || p[i] == p[j]) {
			i++;
			j++;
			next[i] = j;
		}
		else j = next[j];
	}
}

int  kmpFind(string s, string p, string next,int pos ) {
	int i = pos;
	int j = 1;
	while (i <= s[0] && j <= p[0]) {
		if (j == 0 || s[i] == p[j]) {
			i++;
			j++;
		}
		else 
			j = next[j];
	}
	if (j > p[0]) return i - p[0];
	else return 0;
}

int main() {
	int t;
	cin >> t;
	while (t--) {
		string s1, p1, s, p, next1, next;
		cin >> s1 >> p1;
		s = "a" + s1;
		p = "a" + p1;
		getNext(s, next1);
		next = "a" + next1;
		int nums = s.length();
		int key=0;
		for (int m = 1; m <= nums; m++) {
			key=kmpFind(s, p, next, m);
			if (key != 0)
				break;
		}
		cout << key << endl;
	}
	return 0;
}

自己生搬硬套，出错很自然，但是现在无心搞这个啊，要是课前预习好，并且上课没有犯困就好了。先回去处理其他作业吧

 

 

string 定义后需要初始化。

 

 

#include<iostream>
#include<string>
#include<string.h>
const int MAXN = 1000;
using namespace std;

void cal_next(string str, int *next, int len);
int KMP(string str, int slen, string ptr, int plen);

void cal_next(string str, int *next, int len)
{
	next[0] = -1;//next[0]初始化为-1，-1表示不存在相同的最大前缀和最大后缀
	int k = -1;//k初始化为-1
	for (int q = 1; q <= len - 1; q++)
	{
		while (k > -1 && str[k + 1] != str[q])//如果下一个不同，那么k就变成next[k]，注意next[k]是小于k的，无论k取任何值。
		{
			k = next[k];//往前回溯
		}
		if (str[k + 1] == str[q])//如果相同，k++
		{
			k = k + 1;
		}
		next[q] = k;//这个是把算的k的值（就是相同的最大前缀和最大后缀长）赋给next[q]
	}
}

int KMP(string str, int slen, string ptr, int plen)
{
	int *next = new int[plen];
	cal_next(ptr, next, plen);//计算next数组
	for (int j = 0; j < sizeof(next); j++) {
		cout << next[j] << " ";
	}
	cout << endl;
	int k = -1;
	for (int i = 0; i < slen; i++)
	{
		while (k >-1 && ptr[k + 1] != str[i])//ptr和str不匹配，且k>-1（表示ptr和str有部分匹配）
			k = next[k];//往前回溯
		if (ptr[k + 1] == str[i])
			k = k + 1;
		if (k == plen - 1)//说明k移动到ptr的最末端
		{
			//cout << "在位置" << i-plen+1<< endl;
			//k = -1;//重新初始化，寻找下一个
			//i = i - plen + 1;//i定位到该位置，外层for循环i++可以继续找下一个（这里默认存在两个匹配字符串可以部分重叠），感谢评论中同学指出错误。
			return i - plen + 2;//返回相应的位置
		}
	}
	return 0;
}
int main() {
	int t;
	cin >> t;
	while (t--) {
		string s, p;
		cin >> s >> p;
		int key = KMP(s, s.length(), p, p.length());
		cout << key << endl;
	}
	return 0;
}

借鉴了网上的，但是这个的思想和课本上的不大一样

https://blog.youkuaiyun.com/starstar1992/article/details/54913261/

#include<iostream>
#include<string>
#include<string.h>
const int MAXN = 1000;
using namespace std;

void getNext(string p, int*next);
int KMP(string s, string p, int*next);
void getNext(string p, int*next) {
	int j = 0;
	next[0] = -1;
	int k = -1;
	while (j < p.length()) {
		if (k == -1 || p[j] == p[k]) {
			j++;
			k++;
			next[j] = k;
		}
		else {
			k = next[k];
		}
	}
}
int KMP(string s, string p, int*next) {
	int i = 0, j = 0;
	int nums = s.length();
	int nump = p.length();
	while (i < nums && j < nump) {
		if (j == -1 || s[i] == p[j]) {
			i++;
			j++;
			cout << i << " " << j << endl;
		}
		else {
			j = next[i];
		}
		
	}
	if (j > p.length())
		return (i - p.length() + 1);
	else
		return 0;
}

int main() {
	int t;
	cin >> t;
	while (t--) {
		string s, p;
		cin >> s >> p;
		int *next = new int[p.length()];
		getNext(p, next);
		for (int i = 0; i < p.length(); i++) {
			cout << next[i] << " ";
		}
		cout << endl;
		int key = KMP(s, p, next);
		cout << key << endl;
	}
	return 0;
}

 

 

 

改了，并且第一次提交runtime，后来

#include<iostream>
#include<string>
#include<string.h>
using namespace std;

void getNext(string p, int*next);
int KMP(string s, string p, int*next);
void getNext(string p, int*next) {
	int j = 0;
	next[0] = -1;
	int k = -1;
	while (j < p.length()-1) {
		if (k == -1 || p[j] == p[k]) {
			j++;
			k++;
			next[j] = k;
		}
		else {
			k = next[k];
		}
	}
}
int KMP(string s, string p, int*next) {
	int i = 0, j = 0;
	int slen,plen;
	slen = s.length();
	plen = p.length();
	while (i < slen&&j<plen){
		if (j == -1 || s[i] == p[j]) {
			i++;
			j++;
		}
		else {
			j = next[j];
		}
		
	}
	if (j ==plen)
		return (i -j + 1);
	else
		return 0;
}

int main() {
	int t;
	cin >> t;
	while (t--) {
		string s, p;
		cin >> s >> p;
		int *next = new int[p.length()];
		getNext(p, next);
		for (int i = 0; i < p.length(); i++) {
			cout << next[i] << " ";
		}
		cout << endl;
		int key = KMP(s, p, next);
		cout << key << endl;
		delete[] next;
	}
	return 0;
}

把getNExt 函数中

#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
using namespace std;

void getNext(string p, int*next);
int KMP(string s, string p, int*next);
void getNext(string p, int*next) {
	int j = 0;
	next[0] = -1;
	int k = -1;
	while (j < p.length()-1) {
		if (k == -1 || p[j] == p[k]) {
			j++;
			k++;
			next[j] = k;
		}
		else {
			k = next[k];
		}
	}
}
int KMP(string s, string p, int*next) {
	int i = 0, j = 0;
	int slen,plen;
	slen = s.length();
	plen = p.length();
	while (i < slen&&j<plen){
		if (j == -1 || s[i] == p[j]) {
			i++;
			j++;
		}
		else {
			j = next[j];
		}
		
	}
	if (j ==plen)
		return (i -j + 1);
	else
		return 0;
}

int main() {
	int t;
	cin >> t;
	while (t--) {
		string s, p, h;
		cin >> s >> p >> h;
		int *next = new int[p.length()];
		getNext(p, next);
		int key = KMP(s, p, next);
		cout << s << endl;

		if (key != 0) {
			if (p.length() == h.length()) {
				for (int i = key - 1; i < key-1 + h.length(); i++) {
					s[i] = h[i - key + 1];
				}//string 会默认初始化为" "，访问定义以外的空间，也是" " 
			}
			else {
				int numba = p.length() < h.length() ? p.length() : h.length();
				for (int i = key - 1; i < key-1 + numba; i++) {
					s[i] = h[i - key + 1];
				}
				if (numba == p.length()) {
					s.insert(key + numba - 1, h, numba, h.length() - 1);
				}
				else {
					s.insert(key + numba - 1, p, numba, p.length() - 1);
				}
			}
			cout << s << endl;
		}
		else {
			cout << s << endl;
		}
		delete[] next;
	}
	return 0;
}

的 while() 判断条件改成 j<p.length()-1 ，提交成功

 

 

#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
using namespace std;

void getNext(string p, int*next);
int KMP(string s, string p, int*next);
string matched_Prefix_Postfix(string str);
void getNext(string p, int*next) {
	int j = 0;
	next[0] = -1;
	int k = -1;
	while (j < p.length()-1) {
		if (k == -1 || p[j] == p[k]) {
			j++;
			k++;
			next[j] = k;
		}
		else {
			k = next[k];
		}
	}
}
int KMP(string s, string p, int*next) {
	int i = 0, j = 0;
	int slen,plen;
	slen = s.length();
	plen = p.length();
	while (i < slen&&j<plen){
		if (j == -1 || s[i] == p[j]) {
			i++;
			j++;
		}
		else {
			j = next[j];
		}
		
	}
	if (j ==plen)
		return (i -j + 1);
	else
		return 0;
}
string matched_Prefix_Postfix(string str) {
	string front;
	int prs=0;
	for (int i = 1; i < str.length(); i++) {
		string back = str.substr(i, str.length() - i);
		int* next = new int[back.length()];
		getNext(back, next);
		int key = KMP(str, back, next);
		if (key == 1) {
			front = back;
			prs = i;
			break;
		}
	}
	if (prs != 0)
		return front;
	else
		return "empty";

}

int main() {
	int t;
	cin >> t;
	while (t--) {
		string s;
		cin >> s;
		string ans=matched_Prefix_Postfix(s);
		cout << ans << endl;
	}
	return 0;
}

string 的   t=b, 如果t比b大，那么是整个变成了b，还是一部分变成了 b，剩下的还是原来的元素？

 

 

#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
using namespace std;

void getNext(string p, int*next);
int KMP(string s, string p, int*next);
int findLong(string str);
void getNext(string p, int*next) {
	int j = 0;
	next[0] = -1;
	int k = -1;
	while (j < p.length()-1) {
		if (k == -1 || p[j] == p[k]) {
			j++;
			k++;
			next[j] = k;
		}
		else {
			k = next[k];
		}
	}
}
int KMP(string s, string p, int*next) {
	int i = 0, j = 0;
	int slen,plen;
	slen = s.length();
	plen = p.length();
	while (i < slen&&j<plen){
		if (j == -1 || s[i] == p[j]) {
			i++;
			j++;
		}
		else {
			j = next[j];
		}
		
	}
	if (j ==plen)
		return (i -j + 1);
	else
		return 0;
}

int findLong(string str) {
	int num=-1;
	for (int i = 0; i < str.length()-1; i++) {
		for (int j = 1; j <= (str.length()-i)/2; j++) {
			string p = str.substr(i, j);
			int np = p.length();
			int *next = new int[np];
			getNext(p, next);
			int key = KMP(str, p, next);
			if (key != 0) {
					key = 0;
					string ptr = str.substr(i + j, str.length() - j);
					key = KMP(ptr, p, next);
					if (key != 0&& np>num) {//这里特别奇怪，如果用 p.length()就一直判断错误
						num = p.length();
					}
				}
			delete[] next;
		}
	}
	return num;
}
int main() {
	int t;
	cin >> t;
	while (t--) {
		string s;
		cin >> s;
		int ans=findLong(s);
		cout << ans << endl;
	}
	return 0;
}
#include<iostream>
#include<string>
using namespace std;
int main() {
	string s;
	while (getline(cin,s)) {
		s[0] = s[0] - 32;
		for (int i = 1; i < s.length(); i++) {
			if (s[i] == ' ') {
				s[i + 1] = s[i + 1] - 32;
			}
		}
		cout << s << endl;
	}
	return 0;
}

cin 遇到空格和回车就会停止，输入含空格字符串用 getline(cin,s);

 

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