add

Author: Hawstein

20.8

@@ -1,7 +1,60 @@
 #include <iostream>
+#include <cstring>
 using namespace std;
 
+class Trie{
+public:
+    static const int MAX_N = 100 * 100;// 100为主串长度
+    static const int CLD_NUM = 26;
+    int size;
+    int trie[MAX_N][CLD_NUM];
+
+    Trie(const char* s);
+    void insert(const char* s);
+    bool find(const char* s);
+};
+
+Trie::Trie(const char* s){
+    memset(trie[0], -1, sizeof(trie[0]));
+    size = 1;
+    while(*s){
+        insert(s);
+        ++s;
+    }
+}
+
+void Trie::insert(const char* s){
+    int p = 0;
+    while(*s){
+        int i = *s - 'a';
+        if(-1 == trie[p][i]){
+            memset(trie[size], -1, sizeof(trie[size]));
+            trie[p][i] = size++;
+        }
+        p = trie[p][i];
+        ++s;
+    }
+}
+
+bool Trie::find(const char* s){
+    int p = 0;
+    while(*s){
+        int i = *s - 'a';
+        if(-1 == trie[p][i])
+            return false;
+        p = trie[p][i];
+        ++s;
+    }
+    return true;
+}
+
 int main(){
-    cout<<"hey man! Watch your time!"<<endl;
+    Trie tree("mississippi");
+    string patt[] = {
+        "is", "sip", "hi", "sis", "mississippa"
+    };
+    int n = 5;
+    for(int i=0; i<n; ++i)
+        cout<<tree.find((char*)&patt[i][0])<<endl;
     return 0;
 }

20.8.cpp

@@ -0,0 +1,72 @@
+#include <iostream>
+#include <algorithm>
+#include <queue>
+#include <cstdlib>
+using namespace std;
+
+class Median{
+private:
+    priority_queue<int,vector<int>,less<int> > max_heap;//左边的数
+    priority_queue<int,vector<int>,greater<int> > min_heap;//右边的数
+
+public:
+    void Insert(int v);
+    int GetValue();
+};
+
+void Median::Insert(int v){
+    if(max_heap.empty() && min_heap.empty())
+        max_heap.push(v);
+    else if(!max_heap.empty() && min_heap.empty())
+        max_heap.push(v);
+    else if(max_heap.empty() && !min_heap.empty())
+        min_heap.push(v);
+    else{
+        if(v < max_heap.top())
+            max_heap.push(v);
+        else
+            min_heap.push(v);
+    }
+    //调整，保证两个堆的元素数量差别不大于1
+    //不要用hmax_heap.size()-min_heap.size()>1
+    //因为size返回的是unsigned类型，当左边相减得到一个负数时，本来为false
+    //但会被转为一个大的正数，结果为true，出问题
+    while(max_heap.size() > min_heap.size()+1){
+        int data = max_heap.top();
+        min_heap.push(data);
+        max_heap.pop();
+    }
+    while(min_heap.size() > max_heap.size()+1){
+        int data = min_heap.top();
+        max_heap.push(data);
+        min_heap.pop();
+    }
+}
+
+int Median::GetValue(){//中位数为int，由于有除法，也可改为float
+    if(max_heap.empty() && min_heap.empty())
+        return (1<<31); //都为空时，返回int最小值
+    if(max_heap.size() == min_heap.size())
+        return (max_heap.top()+min_heap.top()) / 2;
+    else if(max_heap.size() > min_heap.size())
+        return max_heap.top();
+    else
+        return min_heap.top();
+}
+
+int main(){
+    srand((unsigned)time(0));
+    Median md;
+    vector<int> vi;
+    int num = rand() % 30; //数量是30以内的随机数
+    for(int i=0; i<num; ++i){
+        int data = rand() % 100; //元素是100内的数
+        vi.push_back(data);
+        md.Insert(data);
+    }
+    sort(vi.begin(), vi.end());
+    for(int i=0; i<num; ++i)
+        cout<<vi.at(i)<<" "; //排序的序列
+    cout<<endl<<md.GetValue()<<endl; //中位数
+    return 0;
+}

20.9

@@ -29,6 +29,7 @@ stack<int> Ssort(stack<int> s){
     }
     return t;
 }
+
 int main(){
     srand((unsigned)time(0));
     stack<int> s;

20.9.cpp

@@ -0,0 +1,102 @@
+#include <iostream>
+#include <queue>
+#include <cstring>
+using namespace std;
+
+class ACAutomation{
+public:
+    static const int MAX_N = 1000 * 50;
+    static const int CLD_NUM = 26;
+
+    int size;
+    int fail[MAX_N];
+    int tag[MAX_N];
+    int trie[MAX_N][CLD_NUM];
+
+    void reset();
+    void insert(const char* s);
+    void construct();
+    int query(const char* s);
+};
+
+void ACAutomation::reset(){
+    memset(trie[0], -1, sizeof(trie[0]));
+    tag[0] = 0;
+    size = 1;
+}
+
+void ACAutomation::insert(const char* s){
+    int p = 0;
+    while(*s){
+        int i = *s - 'a';
+        if(-1 == trie[p][i]){
+            memset(trie[size], -1, sizeof(trie[size]));
+            tag[size] = 0;
+            trie[p][i] = size++;
+        }
+        p = trie[p][i];
+        ++s;
+    }
+    ++tag[p];
+}
+
+void ACAutomation::construct(){
+    queue<int> q;
+    fail[0] = 0;
+    for(int i=0; i<CLD_NUM; ++i){
+        if(-1 != trie[0][i]){
+            fail[trie[0][i]] = 0;
+            q.push(trie[0][i]);
+        }
+        else
+            trie[0][i] = 0;
+    }
+    while(!q.empty()){
+        int u = q.front();
+        q.pop();
+        for(int i=0; i<CLD_NUM; ++i){
+            int &v = trie[u][i];
+            if(-1 != v){
+                q.push(v);
+                fail[v] = trie[fail[u]][i];
+                //tag[u] += tag[fail[u]];
+            }
+            else
+                v = trie[fail[u]][i];
+        }
+    }
+}
+
+//返回匹配的模式串个数
+int ACAutomation::query(const char* s){
+    int p = 0, cnt = 0;
+    while(*s){
+        int i = *s - 'a';
+        while(-1==trie[p][i] && p!=0)//无法匹配当前字符，回退到其fail指针
+            p = fail[p];
+        p = trie[p][i];
+        p = p==-1 ? 0 : p;
+        int t = p;
+        while(t!=0 && tag[t]!=-1){
+            cnt += tag[t];
+            tag[t] = -1;
+            t = fail[t];//跳到当前字符的最大后缀，统计模式串出现个数
+        }
+        ++s;
+    }
+    return cnt;
+}
+
+int main(){
+    ACAutomation ac;
+    ac.reset();
+    string patt[] = {
+        "is", "sip", "is", "sis", "mississipp"
+    };
+    int n = 5;
+    for(int i=0; i<n; ++i)
+        ac.insert((char*)&patt[i][0]);
+    ac.construct();
+    cout<<ac.query("mississippi")<<endl;
+    return 0;
+}