排序，查找

快速排序

#include <stdio.h>

int partition(int *a, int first, int last)
{
	int temp = a[first];
	while (last > first){
		while (last > first && a[last] >= temp) last --;
		if (last > first){
			a[first] = a[last];
			first ++;
		}						
		while (last > first && a[first] <= temp) first ++;
		if (last > first){
			a[last] = a[first];
			last --;
		}
	}
	a[first] = temp;
	return first;
}

void myqsort(int a[], int first, int last)
{
	int part;
	if (first < last){
		part = partition(a, first, last);
		myqsort(a, first, part);
		myqsort(a, part+1, last);
	}
	
}

void quicksort(int a[], int n)
{
	int first = 0;
	int last = n-1;
	myqsort(a, first, last);
}

int main()
{
	int a[] = {5, 2, 1, 9, 0, 8, 6, 4, 7, 3};
	int n = sizeof(a)/sizeof(a[0]);
	quicksort(a, n);
	int i;
	for (i = 0; i < n; i++)
		printf("%d ", a[i]);
		
	return 0;
	
}

冒泡排序

#include <stdio.h>

void bubblesort(int a[], int n)
{
	int i, j;
	int temp;
	int flag;
	for (i = 1; i < n; i ++){
		flag = 0;
		for (j = n-1; j >= i; j --){
			if (a[j] < a[j-1]){
				temp = a[j];
				a[j] = a[j-1];
				a[j-1] = temp;
				flag = 1;
			}
		}
		if (flag == 0) break;
	}
}


int main()
{
	int a[]	= {3, 2, 9, 5, 1, 0, 6};
	int n = sizeof(a)/sizeof(a[0]);
	bubblesort(a, n);
	int i;
	for (i = 0; i < n; i ++){
		printf("%d ", a[i]);
	} 
	
	return 0;
}

插入排序

#include <stdio.h>
void insertsort(int a[], int n)
{
	int i, j;
	int temp;
	for (i = 1; i < n; i ++){
		for (j = i; j > 0; j --){
			if (a[j] >= a[j-1]) break;
			else
			{
				temp = a[j];
				a[j] = a[j-1];
				a[j-1] = temp;
			}
		}
	}
}

int main()
{
	int a[] = {3, 2, 8, 7, 0, 1, 6};
	int n = sizeof(a)/sizeof(a[0]);
	
	insertsort(a, n);
	int i;
	for (i = 0; i < n; ++i){
		printf("%d ", a[i]);
	}
	return 0;
}

归并排序

#include <iostream>
using namespace std;

void Merge(int a[], int p, int q, int r)
{
	int n1 = q - p + 1;
	int n2 = r - q;
	int *L = new int[n1 + 1];
	int *R = new int[n2 + 1];
	int i, j, k;
	for (i = 0; i < n1; i++)
		L[i] = a[p + i];
	for (j = 0; j < n2; j++)
		R[j] = a[q + j + 1];

	L[n1] = 0xFFFF, R[n2] = 0xFFFF;

	i = 0; j = 0;
	for (k = p; k <= r; k++){
		if (L[i] <= R[j])
			a[k] = L[i++];
		else
			a[k] = R[j++];
	}
}

void Merge_sort(int a[], int p, int r)
{
	if (p < r){
		int q = (p + r) / 2;
		Merge_sort(a, p, q);
		Merge_sort(a, q + 1, r);
		Merge(a, p, q, r);
	}
}

int main()
{
	int a[] = { 4, 2, 1, 8, 5, 3, 9, 2, 0 };
	int n = sizeof(a) / sizeof(a[0]);
	Merge_sort(a, 0, n - 1);
	for (int i = 0; i < n; i++)
		cout << a[i] << " ";
	cout << endl;
	return 0;
}

堆排序

#include <iostream>
using namespace std;

#define LeftChild(i) (2*(i) + 1)

void Swap(int &a, int &b)
{
	int tmp;
	tmp = a;
	a = b;
	b = tmp;
}
void PercDown(int a[], int i, int N)
{
	int child;
	int tmp;
	for (tmp = a[i]; LeftChild(i) < N; i = child){
		child = LeftChild(i);
		if (child != N - 1 && a[child + 1] > a[child])
			child++;
		if (tmp < a[child])
			a[i] = a[child];
		else
			break;
	}
	a[i] = tmp;
}

void HeapSort(int a[], int N)
{
	int i;
	for (i = N / 2; i >= 0; i--)
		PercDown(a, i, N);
	for (i = N - 1; i > 0; i--){
		Swap(a[0], a[i]);
		PercDown(a, 0, i);
	}
}

int main()
{
	int a[] = { 1, 4, 2, 9, 7, 0, 9, 5, 6, 3 };
	int n = sizeof(a) / sizeof(a[0]);

	HeapSort(a, n);
	for (int i = 0; i < n; i++)
		cout << a[i] << " ";

	cout << endl;
	return 0;
}

二分查找

#include <stdio.h>
int mybsearch(int a[], int n, int target)
{
	int first = 0, last = n-1, mid;
	while (first <= last){
		mid = (first+last)/2;
		if (a[mid] == target) return mid;
		else if (a[mid] < target) first = mid+1;
		else last = mid-1;
	}
	return 0;
}

int main()
{
	int a[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
	int n = sizeof(a)/sizeof(a[0]);
	printf("%d ", mybsearch(a, n, 5));
	return 0;
}