二分法查找 Binary Search

万川先生 — Sun, 21 Aug 2011 04:52:00 GMT

二分法查找（Binary Search)
适用于查找已排序的序列中是否存在某一特定元素。
使用了函数模板：

//万川先生: 2011.08.21
//BinarySearch--二分查找
#include <iostream>
using namespace std;

template <class T>
int binarySearch(T *a, int len, T value)
{
  int min = 0;
  int max = len - 1;

  while (min <= max) {
    int mid = (min + max) / 2;
    if (a[mid] == value)
      return mid;
    else if (a[mid] > value)
      max = mid - 1;
    else
      min = mid + 1;
  }
  return -1;
}

int main(int argc, char* argv[])
{
  double arr[] = {1.1,5.6,7.7,9.1,11.2,18.2,23.3};
  double res = binarySearch(arr,
           sizeof(arr)/sizeof(*arr), 11.2);

  if (res == -1) {
    cout << "Element not found!" << endl;
  }
  else {
    cout << "value is found in array, index is "
     << res << "." << endl;
  }

  return 0;
}

万川先生 2011-08-21 12:52 发表评论

C++博客-chenpingjun1990-文章分类-Algorithm

二分法查找 Binary Search