Standard C++ Library Class Reference

Description

The inplace_merge algorithm merges two sorted consecutive ranges [first, middle) and [middle,

last), and puts the result of the merge into the range [first, last). The merge is stable, that is, if

the two ranges contain equivalent elements, the elements from the first range always precede

the elements from the second.

There are two versions of the inplace_merge algorithm. The first version uses the less than

operator (operator<) as the default for comparison, and the second version accepts a third

argument that specifies a comparison operator.

Complexity

When enough additional memory is available, inplace_merge does at most (last - first) - 1

comparisons. If no additional memory is available, an algorithm with O(NlogN) complexity

(where N is equal to last-first) may be used.

Example

// merge.cpp

#include <algorithm>

#include <vector>

#include <iostream.h>

int main()

{

int d1[4] = {1,2,3,4};

int d2[8] = {11,13,15,17,12,14,16,18};

// Set up two vectors

vector<int> v1(d1,d1 + 4), v2(d1,d1 + 4);

// Set up four destination vectors

vector<int> v3(d2,d2 + 8),v4(d2,d2 + 8),

v5(d2,d2 + 8),v6(d2,d2 + 8);

// Set up one empty vector

vector<int> v7;

// Merge v1 with v2

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),v3.begin());

// Now use comparator

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),v4.begin(),

less<int>());

// In place merge v5

vector<int>::iterator mid = v5.begin();

advance(mid,4);