常见几个排序源码及二分查找源码

void swap(int &a, int &b){int tmp = a;a = b;b = tmp;}

//不使用中间变量的swap函数 

void swap_novar(int &a, int &b){if (a != b){a ^= b;b ^= a;a ^= b;}}

//快排算法实现1

int Median3(int *a, int left, int right){int center = (left + right)/2;if(a[left] > a[center])swap(a[left], a[center]);if(a[left] > a[right])swap(a[left], a[right]);if(a[center] > a[right])swap(a[center], a[right]);swap(a[center], a[right-1]);return a[right-1];}void Qsort1(int *a, int left, int right){if(left >= right)return;int pivot = Median3(a, left, right);int i = left, j = right-1;while(1){while(a[++i] < pivot);while(a[--j] > pivot);if(i < j)swap(a[i], a[j]);elsebreak;}swap(a[i], a[right-1]);Qsort1(a, left, i-1);Qsort1(a, i+1, right);}

//快排算法实现2

void Qsort2(int *a, int left, int right){if(left < right){int pivot = a[left];int i = left, j = right;while(i < j){while(i < j && a[j] >= pivot)j--;if(i < j)a[i++] = a[j];while(i < j && a[i] < pivot)i++;if(i < j)a[j--] = a[i];}a[i] = pivot;Qsort2(a, left, i-1);Qsort2(a, i+1, right);}}

//堆排序 

//堆向上调整，堆插入新元素时调用 //新插入元素在堆末尾，也就是下标为n-1处 //向上调整操作与堆排序无关void MaxHeapFixUp(int a[], int n){int i = n - 1;int tmp = a[i];int father = (i - 1)/2;while(father >= 0 && i != 0){if(a[father] > tmp)break;a[i] = a[father];i = father;father = (i - 1) / 2;}a[i] = tmp;}

//最大堆向下调整，删除堆顶元素时调用（堆排序时使用） void MaxHeapFixDown(int a[], int i, int n){int tmp = a[i];int lchild = 2*i + 1;while(lchild < n){if( (lchild+1) < n && a[lchild] < a[lchild + 1])lchild++;if(a[lchild] < tmp)break;a[i] = a[lchild];i = lchild;lchild = 2*i + 1;}a[i] = tmp;}

//建最大堆

void MakeMaxHeap(int a[], int n)  {  int i;    for (i = n/2 - 1; i >= 0; i--)        MaxHeapFixDown(a, i, n);}  

//堆排序

void HeapSort(int a[], int n){MakeMaxHeap(a, n);int i = n-1;for(i = n-1; i > 0; --i){swap(a[0], a[i]);MaxHeapFixDown(a, 0, i);}}

//冒泡排序

void BubbleSort(int a[], int n){int i, j;for(i = 0; i < n; i++){for(j = 0; j < n-i; j++){if(a[j] > a[j+1])swap(a[j], a[j + 1]);}}}//添加标记flag，当序列已经全部有序后提前结束void BubbleSort2(int a[], int n){int flag = 1;while(flag){flag = 0;for(int j = 0; j < n; j++){if(a[j] > a[j+1]){swap(a[j], a[j + 1]);flag = 1;}}n--;}}

//直接插入排序(Insertion Sort)：
//每次将一个待排序的记录，按其关键字大小插入到前面已经排好序的子序列中的适当位置，直到全部记录插入完成为止。

void InsertSort(int a[], int n){int i = 0;for(i = 1; i < n; i++){int tmp = a[i];int j = i - 1;while(j >= 0 && a[j] > tmp){a[j+1] = a[j];j--;}a[j+1] = tmp;}}

//希尔排序：先取一个小于n的整数d1作为第一个增量，把文件的全部记录分组。所有距离为d1的倍数的记录放在同一个组中。先在各组内进行直接插入排序；然后，取第二个增量d2<d1重复上述的分组和排序，直至所取的增量dt=1(dt<dt-l<…<d2<d1)，即所有记录放在同一组中进行直接插入排序为止。 

void ShellSort(int a[], int n){int gap, i, j;for(gap = n/2; gap > 0; gap /= 2){for(i = 0; i < gap; i++){for(j = i + gap; j < n; j += gap){int tmp = a[j];int k = j - gap;while(k >= 0 && a[k] > tmp){a[k + gap] = a[k];k -= gap;}a[k + gap] = tmp;}}}}

//直接选择排序

void SelectSort(int a[], int n){int i, j;for(i = 0; i < n; ++i){int min = a[i], k = i;for(j = i + 1; j < n; j++){if(a[j] < min){min = a[j];k = j;}}swap(a[i], a[k]);}} 

//归并排序

void merge(int a[], int tmparray[], int lpos, int rpos, int rightend){int leftend = rpos -  1;int tmppos = lpos;int num = rightend - lpos + 1;int i;while(lpos <= leftend && rpos <= rightend){if(a[lpos] < a[rpos])tmparray[tmppos++] = a[lpos++];elsetmparray[tmppos++] = a[rpos++];}while(lpos <= leftend)tmparray[tmppos++] = a[lpos++];while(rpos <= rightend)tmparray[tmppos++] = a[rpos++];for(i = 0; i < num; ++i, rightend--){a[rightend] = tmparray[rightend];}}void Msort(int a[], int tmparray[], int left, int right){int mid;if(left < right){mid = (left + right)/2;Msort(a, tmparray, left, mid);Msort(a, tmparray, mid + 1, right);merge(a, tmparray, left, mid + 1, right);}}void MergeSort(int a[], int n){int *tmparray = (int *)malloc(sizeof(int) * n);if(tmparray != NULL){Msort(a, tmparray, 0, n-1);free(tmparray);}}

二分查找源码：

int binary_search(int array[], int n, int value){int left = 0;int right = n-1;while(left <= right){int mid = left + ((<span style="color:#ff0000;">unsigned int</span>(right - left))>>1); //凡是右移操作时，一定要考虑有符号数符号扩展的问题if(array[mid] > value){right = mid - 1;}else if(array[mid] < value){left = mid + 1;}elsereturn mid;}return -1;}