二分查找：
#include <stdio.h> #include <stdlib.h> #include <string.h> //法一，非递归实现 int second_find(int *L,int key,int low,int sizearray) { int mid = 0; int high = sizearray - 1; while(low <= high) { mid = (low + high)/2 if (key < L[mid]) { high = mid - 1; } else if (key > L[mid]) { low = mid + 1; } else { return mid; } } } //法二,递归实现 int send_find2(int *L,int key,int low,int high) { if (low <= high) { int mid = (low+high)/2; if (key < L[mid]) { send_find2(L,key,low,mid -1); } else if(key > L[mid]) { send_find2(L,key,mid + 1,high); } else { return mid; } } else { return -1; } } int main(int argc,char *argv) { int a[5] = {1,2,3,4,5}; int num = second_find(a,2,0,sizeof(a)/sizeof(a[0])); }快速排序：
int paintion(int *L,int low,int high) { int poit = L[low]; while(low < high) { while(low < high && L[low] <= poit) low++; swap(L,low,high); while(low < high && L[high] >= poit) high--; swap(L,low,high); } return low; } void Qsort(int *L,int low,int high) { int poit = 0; if (low < high) { poit = paintion(L,low,high); Qsort(L,poit+1,high); Qsort(L,low,poit - 1); } } int main(int argc,char *argv[]) { return 0; }快速排序优化
#include <stdio.h> int paintion(int *L,int low,int high) { int poit = L[low]; while(low < high) { while(low < high && L[high] >= poit) high--; L[low] = L[high]; while(low < high && L[low] <= poit) low++; L[high] = L[low]; } L[low] = poit; return low; } void Qsort(int *L,int low,int high) { if (low < high) { int poit = paintion(L,low,high); Qsort(L,low,poit - 1); Qsort(L,poit + 1,high); } } int main(int argc,char *argv[]) { int a[20] = {10,9,16,3,17,7,19,20,11,1,15,12,4,5,14,2,6,18,8,13}; Qsort(a,0,19); int i = 0; for (;i<20;i++) { printf("a:%d\n",a[i]); } return 0; }