算法导论学习之归并排序

惭愧，又好久没看《算法导论》了。上次看《算法导论》的归并排序算法，后来自己写了段代码，实现了算法，不过有问题，一直也没找出问题来。今天趁着礼拜天有时间，调试一下代码。时间不早了，明天还得上班，有时间我会给代码加段注释，以及我在写这段代码的时候，遇到的问题与大家分享，防止大家也犯类似的错误。

// mergeSort.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "iostream"
using namespace std;
void printArray(int a[], int beg, int end) {
for (int i = beg; i < end+1; i++) {
cout << a[i] << "  ";
}
cout << endl;
}

void merge(int a[], int left, int middle, int right) {
int leftLen = middle - left + 1;
int rightLen = right - middle;

int* tempLeft = new int[leftLen+1];
int* tempRight = new int[rightLen+1];

for (int i = 0; i < leftLen; i++) {
tempLeft[i] = a[left + i];
}

for (int j = 0; j < rightLen; j++) {
tempRight[j] = a[j+left+leftLen];
}

tempLeft[leftLen] = 100000;
tempRight[rightLen] = 100000;

int i = 0;
int j = 0;

for (int k = left; k < right+1; k++) {
if (tempLeft[i] < tempRight[j]) {
a[k] = tempLeft[i];
i++;
} else {
a[k] = tempRight[j];
j++;
}
}

}

void mergeSort(int a[], int left, int right) {
int middle = (left+right)/2;
if (left < right) {
mergeSort(a, left, middle);
mergeSort(a, middle+1, right);
cout << "before merge:" << endl;
printArray(a, left, right);

merge(a, left, middle, right);
cout << "merged:" << endl;
printArray(a, left, right);

}

}

void test1() {
int a[10] = {7, 6, 5, 9, 0, 3, 1, 2, 8, 4};
mergeSort(a, 0, 9);
cout << "final sort:" << endl;
for (int i = 0; i < 10; i++) {
cout << a[i] << "  ";
}
}

int _tmain(int argc, _TCHAR* argv[])
{
test1();

int b;
cin >> b;
return 0;
}