二分查找(折半查找):对于已排序,若无序,需要先排序
// 二分查找(折半查找):对于已排序,若无序,需要先排序 // 非递归 int BinarySearch(vector<int> v, int value) { if (v.size() <= 0) return -1; int low = 0; int high = v.size() - 1; while (low <= high) { int mid = low + (high - low) / 2; if (v[mid] == value) return mid; else if (v[mid] > value) high = mid - 1; else low = mid + 1; } return -1; } // 递归 int BinarySearch2(vector<int> v, int value, int low, int high) { if (low > high) return -1; int mid = low + (high - low) / 2; if (v[mid] == value) return mid; else if (v[mid] > value) return BinarySearch2(v, value, low, mid - 1); else return BinarySearch2(v, value, mid + 1, high); }