分治思想下的递归二分查找兼泛型sort算法

23-divide_and_conconquer/binary_search/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.17)
+project(binary_search)
+
+set(CMAKE_CXX_STANDARD 14)
+
+add_executable(binary_search main.cpp)

23-divide_and_conconquer/binary_search/main.cpp

@@ -0,0 +1,69 @@
+#include <iostream>
+#include <vector>
+#include <random>
+#include <algorithm>
+
+#include <iomanip>
+
+using namespace std;
+
+
+template <typename T>
+int binary_search(const vector<T> &sample,const T item, int begin, int end) {
+
+    if(begin > end) {
+        return -1;
+    } else {
+        int middle_key = begin+(end-begin)/2;
+        if(sample[middle_key] == item) {
+            return middle_key;
+        } else if(sample[middle_key] > item) {
+            return binary_search(sample, item, begin, middle_key-1);
+        } else {
+            return binary_search(sample, item, middle_key+1, end);
+        }
+    }
+}
+
+template <typename T>
+void show(const T &sample) {
+    for(int i = 1; i <= 100; ++i) {
+        cout<<setw(8)<<sample[i-1];
+        if(i%10 == 0) {
+            cout<<endl;
+        }
+    }
+    cout<<endl;
+}
+int main() {
+    std::cout << "Hello, World!" << std::endl;
+    default_random_engine e(0);
+    uniform_int_distribution<int> u(1, 10000);
+    vector<int> sample;
+    for(int i = 0; i< 100; ++i) {
+        sample.push_back(u(e));
+    }
+    show(sample);
+
+
+    sort(sample.begin(), sample.end(), greater<int>());
+    show(sample);
+
+    sort(sample.begin(), sample.end());
+    show(sample);
+
+
+
+
+    cout<<binary_search(sample, 4940, 0, sample.size())<<endl;
+    cout<<binary_search(sample, 7534, 0, sample.size())<<endl;
+    cout<<binary_search(sample, 9999, 0, sample.size())<<endl;
+//
+//    cout<< setw(4) <<123 <<1234<<endl;
+//    cout << 1 <<setw(7) << 1234 << endl;
+//    cout << 1 << setw(7) << 1234567891234 << endl;
+//    cout << 1 << 1234 << setw(7) << endl;
+
+
+    return 0;
+}