【本文链接】
http://www.cnblogs.com/hellogiser/p/quicksort-recursively-and-non-recursively.html
【代码】
C++ Code
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// 69_QuickSort_NonRecursive.cpp : Defines the entry point for the console application.
// /* version: 1.0 author: hellogiser blog: http://www.cnblogs.com/hellogiser date: 2014/9/18 */ #include "stdafx.h" #include "iostream" #include <ctime> #include <algorithm> #include <stack> using namespace std; void myswap(int &a, int &b) { int t = a; a = b; b = t; } void print(int *a, int n) { for (int i = 0; i < n; i++) { cout << a[i] << " "; } cout << endl; } //======================================================== // recursively //======================================================== int partition1(int *a, int left, int right) { // a[left,...p-1]<=a[p]<a[p+1,...right] int i = left; int j = right; int key = a[left]; while(i < j) { while(a[i] <= key) i++; while(a[j] > key) j--; if (i < j) { myswap(a[i], a[j]); } } // left---j---i---right myswap(a[left], a[j]); return j; } int partition2(int *a, int left, int right) { // left, a[left+1...i]<=key, a[i+1,...j-1]>key int i = left; int j = left + 1; int key = a[left]; while(j <= right) { if (a[j] < key) { i++; // so that a[i]>=key myswap(a[i], a[j]); } j++; } //left---i---right---j myswap(a[left], a[i]); return i; } void quicksort_r(int *a, int left, int right) { if (left < right) { int p = partition1(a, left, right); quicksort_r(a, left, p - 1); quicksort_r(a, p + 1, right); } } void QuickSort_Recursively(int *a, int n) { if (a == NULL || n <= 1) return; quicksort_r(a, 0, n - 1); } //======================================================== // non recursively //======================================================== void quicksort_non_r(int *a, int left, int right) { // view [left,right] range as a node, which then has 2 child nodes [left,p-1] and [p+1,right] after partitioning if (left >= right) return; // init stack with one range node stack<int> s; s.push(left); s.push(right); int temp_right, temp_left; int p; while(!s.empty()) { temp_right = s.top(); s.pop(); temp_left = s.top(); s.pop(); if (temp_left < temp_right) { p = partition1(a, temp_left, temp_right); // add node [left,p-1] and [p+1,right] to stack s.push(temp_left); s.push(p - 1); s.push(p + 1); s.push(temp_right); } } } void QuickSort_NonRecursively(int *a, int n) { if (a == NULL || n <= 1) return; quicksort_non_r(a, 0, n - 1); } typedef void (*fun)(int *a, int n); void test_base(int *a, int n, fun f) { print(a, n); f(a, n); print(a, n); cout << "============================== "; } void test_recursively() { srand((unsigned int)time(NULL)); const int n = 10; int a[n]; for (int i = 0; i < n; i++) { a[i] = rand() % 100; } cout << "recursively..." << endl; test_base(a, n, QuickSort_Recursively); } void test_non_recursively() { srand((unsigned int)time(NULL)); const int n = 20; int a[n]; for (int i = 0; i < n; i++) { a[i] = rand() % 100; } cout << "non recursively..." << endl; test_base(a, n, QuickSort_NonRecursively); } void test_main() { test_recursively(); test_non_recursively(); } int _tmain(int argc, _TCHAR *argv[]) { test_main(); return 0; } /* recursively... 43 5 68 83 74 12 80 61 84 48 5 12 43 48 61 68 74 80 83 84 ============================== non recursively... 43 5 68 83 74 12 80 61 84 48 67 95 57 2 17 17 98 94 17 76 2 5 12 17 17 17 43 48 57 61 67 68 74 76 80 83 84 94 95 98 ============================== */ |