折半查找

//二分法查找int as_bi_search(int a[],int n,int e)//数组升序排列{int mid;int left = 0;int right = n - 1;while(left < right){mid = (left + right) / 2;if(e == a[mid]){return mid ;}if(e<a[mid]){left = mid + 1;}if(e>a[mid]){right = mid - 1;}}return mid;}int de_bi_search(int a[],int n,int e)//数组降序排列{int mid;int left = 0;int right = n - 1;while(left < right){mid = (left + right) / 2;if(e == a[mid]){return mid ;}if(e>a[mid]){left = mid + 1;}if(e<a[mid]){right = mid - 1;}}return mid;}int main(){int a[] = {11,10,9,8,7,6,5,4,3,2,1};    int n = sizeof(a)/sizeof(a[0]);//数组长度int ret = de_bi_search(a,11,6);printf("%d\n",a[ret]);printf("%d\n",ret);return 0;}//折半查找；前题条件必须是有序数组，并且按照一定的顺序排好顺序