Question

#include <algorithm>有什么作用？

Answer 1

#include <algorithm>是一个头文件，该头文件包含了一些算法，程序开头加上这个头文件，就可以直接调用里面的函数了，不用再自己手写。但是一些复杂的算法还是要自己写的。另外可以看看这个 http://www.cplusplus.com/reference/algorithm/

Answer 2

当用到标准库里的算法的时候，比如find函数之类的时候就要用到这个头文件了~

Answer 3

Standard Template Library: Algorithms
The header <algorithm> defines a collection of functions especially designed to be used on ranges of elements.

A range is any sequence of objects that can be accessed through iterators or pointers, such as an array or an instance of some of the STL containers. Notice though, that algorithms operate through iterators directly on the values, not affecting in any way the structure of any possible container (it never affects the size or storage allocation of the container).

Functions in <algorithm>
Non-modifying sequence operations:

all_of
Test condition on all elements in range (function template )
any_of
Test if any element in range fulfills condition (function template )
none_of
Test if no elements fulfill condition (function template )
for_each
Apply function to range (function template )
find
Find value in range (function template )
find_if
Find element in range (function template )
find_if_not
Find element in range (negative condition) (function template )
find_end
Find last subsequence in range (function template )
find_first_of
Find element from set in range (function template )
adjacent_find
Find equal adjacent elements in range (function template )
count
Count appearances of value in range (function template )
count_if
Return number of elements in range satisfying condition (function template )
mismatch
Return first position where two ranges differ (function template )
equal
Test whether the elements in two ranges are equal (function template )
is_permutation
Test whether range is permutation of another (function template )
search
Search range for subsequence (function template )
search_n
Search range for elements (function template )

Modifying sequence operations:

copy
Copy range of elements (function template )
copy_n
Copy elements (function template )
copy_if
Copy certain elements of range (function template )
copy_backward
Copy range of elements backward (function template )
move
Move range of elements (function template )
move_backward
Move range of elements backward (function template )
swap
Exchange values of two objects (function template )
swap_ranges
Exchange values of two ranges (function template )
iter_swap
Exchange values of objects pointed to by two iterators (function template )
transform
Transform range (function template )
replace
Replace value in range (function template )
replace_if
Replace values in range (function template )
replace_copy
Copy range replacing value (function template )
replace_copy_if
Copy range replacing value (function template )
fill
Fill range with value (function template )
fill_n
Fill sequence with value (function template )
generate
Generate values for range with function (function template )
generate_n
Generate values for sequence with function (function template )
remove
Remove value from range (function template )
remove_if
Remove elements from range (function template )
remove_copy
Copy range removing value (function template )
remove_copy_if
Copy range removing values (function template )
unique
Remove consecutive duplicates in range (function template )
unique_copy
Copy range removing duplicates (function template )
reverse
Reverse range (function template )
reverse_copy
Copy range reversed (function template )
rotate
Rotate left the elements in range (function template )
rotate_copy
Copy range rotated left (function template )
random_shuffle
Randomly rearrange elements in range (function template )
shuffle
Randomly rearrange elements in range using generator (function template )

Partitions:

is_partitioned
Test whether range is partitioned (function template )
partition
Partition range in two (function template )
stable_partition
Partition range in two - stable ordering (function template )
partition_copy
Partition range into two (function template )
partition_point
Get partition point (function template )

Sorting:

sort
Sort elements in range (function template )
stable_sort
Sort elements preserving order of equivalents (function template )
partial_sort
Partially sort elements in range (function template )
partial_sort_copy
Copy and partially sort range (function template )
is_sorted
Check whether range is sorted (function template )
is_sorted_until
Find first unsorted element in range (function template )
nth_element
Sort element in range (function template )

Binary search (operating on partitioned/sorted ranges):

lower_bound
Return iterator to lower bound (function template )
upper_bound
Return iterator to upper bound (function template )
equal_range
Get subrange of equal elements (function template )
binary_search
Test if value exists in sorted sequence (function template )

Merge (operating on sorted ranges):

merge
Merge sorted ranges (function template )
inplace_merge
Merge consecutive sorted ranges (function template )
includes
Test whether sorted range includes another sorted range (function template )
set_union
Union of two sorted ranges (function template )
set_intersection
Intersection of two sorted ranges (function template )
set_difference
Difference of two sorted ranges (function template )
set_symmetric_difference
Symmetric difference of two sorted ranges (function template )

Heap:

push_heap
Push element into heap range (function template )
pop_heap
Pop element from heap range (function template )
make_heap
Make heap from range (function template )
sort_heap
Sort elements of heap (function template )
is_heap
Test if range is heap (function template )
is_heap_until
Find first element not in heap order (function template )

Min/max:

min
Return the smallest (function template )
max
Return the largest (function template )
minmax
Return smallest and largest elements (function template )
min_element
Return smallest element in range (function template )
max_element
Return largest element in range (function template )
minmax_element
Return smallest and largest elements in range (function template )

Other:

lexicographical_compare
Lexicographical less-than comparison (function template )
next_permutation
Transform range to next permutation (function template )
prev_permutation
Transform range to previous permutation (function template )

Answer 4

你现在还没有到用它的时候 ，你先学基础 多看书 到时候 你就知道了