二分查找：
binarysearch考的比較多，它適用于已經排序的元素中的查找
int binarySearch(int a[],int len,int value){
int low = 0;
int high = len -1;
while(low<=high) //注意搜索條件，有可能兩者會相等
{
int mid = (low+high)/2;
if(a[mid]==value) return mid;
else if(a[mid]>value) high = mid -1;
else low = mid + 1;
}
return -1;
}
int main()
{
int a[] = {1,2,3,4,5,6,7,8,9,10};
int rec = binarySearch(a,10,4);
if(rec==-1)
printf("Not found\n");
else
printf("value is found %d \n",rec);
return 0;
}
快速排序
對冒泡算法的擴展
int partition(int a[],int low,int high){
int temp = a[low];
while(low<high)
{
while(low<high && a[high]>=temp) --high;
a[low] = a[high];
while(low<high && a[low]<=temp) ++low;
a[high] = a[low];
}
a[low] = temp;
return low;
}
void Qsort(int a[],int begin,int end)
{
int rec;
if(begin<end)
{
rec = partition(a,begin,end);
printf("rec is %d\n",rec);
Qsort(a,begin,rec-1);
Qsort(a,rec+1,end);
}
}
int main()
{
int a[] = {1,4,0,-3,90,7,9,23};
Qsort(a,0,7);
int i =0;
for(;i<8;i++)
printf("%d\t",a[i]);
return 0;
}