Node * MergeRecursive(Node *head0, Node *head1)
{if (head0 == NULL){return head1;}if (head1 == NULL){return head0;}Node *head = NULL;if (head0->data < head1->data){head = head0;head->next = MergeRecursive(head0->next, head1);}else{head = head1;head->next = MergeRecursive(head0, head1->next);}return head;
}

bool IsAscendingList(Node *head)
{Node *p = head; while (p->next != NULL){if (p->data > p->next->data){return false; }p = p->next; }return true;
}

int _tmain(int argc, _TCHAR* argv[])
{int data0[5] = { 1, 3, 9, 8, 10}; //int data1[7] = { 9, 1, 2, 4, 6, 10}; int data1[7] = { 9, 4, 7, 6, 6};int secMax0 = FindSecondMax(data0, sizeof(data0) / sizeof(data0[0])); int secMax1 = FindSecondMax(data1, sizeof(data1) / sizeof(data1[0]));
}int FindSecondMax(int *data, int dataLength)
{if (dataLength <= 1){printf("The length of data should be more than 1."); return -1; }int max = data[0]; int secondMax = MIN_INT;for (int i = 1; i < dataLength; i++){if (data[i] > max){secondMax = max;max = data[i];}else{if (data[i] > secondMax){secondMax = data[i]; }}}return secondMax;
}

int _tmain(int argc, _TCHAR* argv[])
{int a = 18; int b = 32; // Swap withouth other variables.  3 times XOR will swap two values. (1^1 = 0, 0^0 =0, 1^0 =1, 0^1 =1). a ^= b; b ^= a; a ^= b; printf("a:%d, b:%d", a, b); // method2a = a + b; b = a - b; a = a - b; printf("a:%d, b:%d", a, b); }

// Assuming the char is ASCII
char FirstSingleChar(char *str)
{int bitmap[255]; memset(bitmap, 0, 255 * sizeof(int)); char *p = str;while (*p != '\0'){bitmap[*p]++; p++; }p = str;  while (*p!='\0'){if (bitmap[*p] == 1){return *p; }}return '\0';
}

int ConvertStrToInt(char *str)
{char *p = str; int result = 0; int asciiToInt = 0; bool isPostive = true; if (*p == '-'){isPostive = false;p++; }else if (*p == '+'){p++; }while (*p != '\0'){if (IsNumber(*p)){asciiToInt = *p - '0';result = result * 10 + asciiToInt;p++;}else{//Had better throw exception here.printf("Illegal number: %c", *p); break; }}if (!isPostive){result = 0 - result; }return result;
}

int _tmain(int argc, _TCHAR* argv[])
{// char *strForTest = "+345abc" will cause "access violation writing location". http://stackoverflow.com/questions/14664510/access-violation-writing-locationchar strForTest[] = "I like money"; ReverseWordsInSentence(strForTest);
}void ReverseString(char *str)
{int strLength = strlen(str); ReverseStringInFixedLength(str, strLength);
}void ReverseStringInFixedLength(char *str, int strLength)
{char *p1 = str;char *p2 = str + strLength -1;char tmp;while (p1 < p2){// Swap two chars. tmp = *p1;*p1 = *p2;*p2 = tmp;p1++;p2--;}
}

void ReverseWordsInSentence(char *sen)
{ReverseString(sen); char *pStartOfWord = sen; char *p = pStartOfWord; while (*p != '\0'){// Skip blank spaces. while (*p == ' ' && *p != '\0'){p++; }pStartOfWord = p; while (*p != ' ' && *p != '\0'){p++; }int wordLength = p - pStartOfWord; ReverseStringInFixedLength(pStartOfWord, wordLength);}
}

For sorted array,  the time complexity is O(n).
For unsorted array, we may do a quick sort and then call our method.  The time complexity is O(nlogn).Here is the C++ sample codes, and I have checked it works well. int _tmain(int argc, _TCHAR* argv[])
{int nums[7] = { 1, 2, 3, 3, 4, 4, 5 }; printUniquePairs(nums, 7, 7); }void printUniquePairs(int *numbers, int numbersLength, int expectedSum)
{int sum = 0; //Augrments judgements. e.g. Null, length. if (numbersLength < 2){printf("Number length should be more than 2.");return; }// Quick sort. QuickSort(numbers); // Use two points (left, and right) moving from two sides into the center.int *p1 = numbers; int *p2 = numbers + numbersLength - 1; int previousP1Value; int previousP2Value; while (p1 < p2){sum = *p1 + *p2; previousP1Value = *p1;previousP2Value = *p2;if (sum == expectedSum){printf("Print unique pair: %d, %d.", *p1, *p2);p1++; p2--; // If the value is duplicated, then skip. if (previousP1Value == *p1){p1++;}if (previousP2Value == *p2){p2--;}}else if (sum < expectedSum){p1++; // If the value is duplicated, then skip. if (previousP1Value == *p1){p1++; }}else if (sum > expectedSum){p2--; if (previousP2Value == *p2){p2--; }}}