快速排序和背包问题的C++实现代码,其中快速排序采用数组中第一个元素、最后一个元素以及中间元素的中间值作为枢轴。-Quick Sort and the knapsack problem of C++ code, including the use of quick sort of the first element of the array, the last element, as well as the middle element as the pivot of the median.