常見基礎演算法筆記

一些常見的基礎演算法(未完待續)

快速排序

int partition(int left,int right,int arr[]){    int i = left;    int j = right;    int value = arr[left];    while (j > i)    {        //從右邊j開始找到一個比value小的值        while (j > i && arr[j] >= value)            j--;        if (j > i)        {            arr[i] = arr[j];            i++;        }        //從左邊i開始找到一個比value大的值        while (j > i && arr[i] <= value)            i++;        if (j > i)        {            arr[j] = arr[i];            j--;        }    }    //i=j時代表所有比value大的值都到了右邊，比value小的到了左邊    arr[i] = value;    return i;}

void quickSort(int arr[], int left, int right){    if (left < right)    {        int i = partition(left, right,arr);        quickSort(arr, left, i - 1);        quickSort(arr, i + 1, right);    }}void quickSortTest(){    int arr[10] = { 1, 34, 5, 6, 8, 12, 5, 9, 345, 0 };    int n = 10;    cout << "==================quickSort====================" << endl;    for (int i = 0; i <= n - 1; i++)    {        cout << arr[i] << "\t";    }    cout << endl;    quickSort(arr, 0, 9);    for (int i = 0; i <= n - 1; i++)    {        cout << arr[i] << "\t";    }    cout << endl;}

堆排序

include //假設第i個節點的左右子樹已經是最大堆，加入第//i個節點後重新調整堆void heapAdjust(int arr[], int i, int size){    int l = 2*i;    int r = l+1;    int max = i;    if(i<=(size/2)){  //非葉子節點才需調整        if(l<=size&&arr[l]>arr[max])        max = l;    if(r<=size&&arr[r]>arr[max])        max = r;    if(max!=i){        arr[max] ^= arr[i];        arr[i] ^= arr[max];        arr[max] ^= arr[i];        //int temp = arr[i];        //arr[i] = arr[max];        //arr[max] = temp;        heapAdjust(arr, max, size);    }    }}//建立最大堆void buildHeap(int arr[], int heapsize){    int middle = heapsize/2;    for(int i=middle;i>=1;i--)        heapAdjust(arr,i,heapsize);}//堆排序void heapSort(int arr[], int size){    buildHeap(arr,size);    for(int i=size;i>=2;i--){        //arr[i] ^= arr[1];    //arr[1] ^= arr[i];    //arr[i] ^= arr[1];    arr[i] += arr[1];    arr[1] = arr[i]-arr[1];    arr[i] = arr[i]-arr[1];    heapAdjust(arr,1,i-1);    }}void printArr(int arr[], int n){    int i = -1;    while(i++

插入排序

void insertSort(){ int arr[10] = { 1, 34, 5, 6, 8, 12, 5, 9, 345, 0 }; int n = 10; cout << "==================insertSort====================" << endl; for (int i = 0; i <= n - 1; i++) { cout << arr[i] << "\t"; } cout << endl; for (int i = 1; i <= n - 1; i++) { int j; int temp = arr[i]; //內迴圈將已排序的且比arr[i]大的往前挪 for (j = i - 1; j >= 0 && arr[j] > temp; j--) { arr[j + 1] = arr[j]; } //最後將最初的arr[i]值放到空出的位置 arr[j + 1] = temp; } for (int i = 0; i <= n - 1; i++) { cout << arr[i] << "\t"; }}

選擇排序

void selectSort(){ int arr[10] = { 1, 34, 5, 6, 8, 12, 5, 9, 345, 0 }; int n = 10; cout << "==================selectSort====================" << endl; for (int i = 0; i <= n - 1; i++) { cout << arr[i] << "\t"; } cout << endl; for (int i = 0; i <= n - 2; i++) { int key = i; //內迴圈找到第i大的值的下標 for (int j = i + 1; j <= n - 1; j++) { if (arr[j] < arr[key]) { key = j; } } int value = arr[i]; arr[i] = arr[key]; arr[key] = value; } for (int i = 0; i <= n - 1; i++) { cout << arr[i] << "\t"; }}

按層列印二叉樹

#include Queue q = new Queue();void printBinaryTree(Node *n){ q.put(n); Node *next = NULL; while(NULL!=(next=q.get())) { if(next->val!=NULL) std::cout<value; if(next->left!=NULL) q.put(next->left); if(next->right!=NULL) q.put(next->right); }}

後序遍曆二叉樹

void postorder(Node root){ if(root == NULL) return; postorder(root->left); postorder(root->right); visit(root);}void postOrder(Node root){ Stack stack = new Stack(); Node tmp = root; while(tmp!=NULL || !stack.empty()) { if(tmp!=NULL) { stack.push(tmp,"left"); tmp = tmp->left; } else { s = stack.pop(); tmp = s.tmp; tag = s.tag; if(tag=="right") { visit(tmp); tmp = NULL; } else { stack.push(tmp,"right"); tmp = tmp->right; } } }}

單鏈表相關(待完善)

//單鏈表反轉void reverse1(node **head){ node *temp; node *op; temp = *head; op = temp->next; (*head)->next = NULL; while(op) { //儲存原始op的下一個 temp = op->next; //拆開鏈表 op->next = *head; //移動head *head = op; //移動op op = temp; }}void reverse2(node **head){ //使用棧先進後出}//反向列印單鏈表void reversePrint(node *head){ if (head->next != NULL) { reversePrint(head->next); printf("%d\n",head->next->data); }}

數組去重

function cleanArray(arr){ var hash = {}; var len = arr.length; for (var i = 0; i < len; i++) { if(undefined == hash[arr[i]]) hash[arr[i]] = arr[i]; }; return hash;}//testcasevar arr = [1,2,3,'1','3',45,123,2,3,45,9,9,"test","fadsa","test"];console.log(cleanArray(arr));//output Object {1: 1, 2: 2, 3: 3, 9: 9, 45: 45, 123: 123, test: "test", fadsa: "fadsa"}

求字元數組全排列

function permute(strpre, str){ if(str.length==0){ console.log(strpre); }else{ var l = str.length; for(var i=0;i

二分尋找

int binarySearch(int arr[], int l, int r, int k){ while(l<=r){ int m = l+(r-l)/2; if(arr[m]==k) return m; if(arr[m]>k) r = m+1; else l = m-1; } return -1;}int binarySearch1(int arr[], int l, int r, int k){ if(r>=l){ int m = l+(r-l)/2; if(arr[m]==k) return m; if(arr[m]>k) binarySearch1(arr, l, m-1, k); else binarySearch1(arr, m+1, r, k); } return -1;}

字串反轉

#include #include void reverse1(char *s){ char *p1,*p2; char c; p1 = s; p2 = s+strlen(s)-1; while(p11){ char c = *s; *s = *(s+tail-1); *(s+tail-1) = c; reverse4(s+1,tail-2); }}

字串複製

void copy(char *s, char *d){ while(*s!='\0'){ *d++ = *s++; } *d = '\0';}

以上就介紹了常見基礎演算法筆記，包括了方面的內容，希望對PHP教程有興趣的朋友有所協助。

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