基本STL算法库使用

1、 count_if 和 lambda联用

	vector<int> vec;
	for (int i = 0; i < 20; i++) {
		vec.push_back(i);
	}
	//count_if 
	int num = count_if(vec.begin(), vec.end(),
		[](int x) { return x > 1 && x < 9; });
	cout << "大于2小于10的个数:" << num << endl;

2、 count

	//count 
	vec.push_back(19);
	int n = count(vec.begin(), vec.end(), 19);
	cout << "vec中19的个数:" << n << endl;

same as

 int num = count_if(vec.begin(),vec.end(),[](int x){ return} x == 19;})

3、 min max

	vector<int>::iterator minIter;
	minIter = min_element(vec.begin(), vec.end());
	vector<int>::iterator maxIter;
	maxIter = max_element(vec.begin(),vec.end());
	cout << "min:" << *minIter << " max:" << *maxIter << endl;
	pair<vector<int>::iterator, vector<int>::iterator> iterPairs;
	iterPairs = minmax_element(vec.begin(), vec.end());
	cout << "min:" << *iterPairs.first << " max:" << *iterPairs.second << endl;

4、 自定义比较函数，获取最大最小值

        vector<int> vec1; //vec1 = {12,32,91,99,101}
	vec1.push_back(12);
	vec1.push_back(32);
	vec1.push_back(91);
	vec1.push_back(66);
	vec1.push_back(101);
	iterPairs = minmax_element(vec1.begin(), vec1.end(), [](int x, int y) {
		if (x % 10 != y % 10) {
			return(x % 10 < y % 10);
		}
		else { return x < y; }
	});
	cout << "min:" << *iterPairs.first << " max:" << *iterPairs.second << endl;

5、 Linear Searching

return first match

find find_if find_if_not

	auto  iter = find_if(vec1.begin(), vec1.end(), [](int x) {return x > 100; });
	if (iter != vec1.end()) {
		cout << "suceess find" <<*iter<<endl;
	}
	iter = find(vec1.begin(), vec1.end(), 12);
	iter = find_if_not(vec1.begin(), vec1.end(), [](int x) { return x > 100; });
	if (iter != vec1.end()) {
		cout << *iter << endl;
	}

6、search

search_n search find_end

	auto iter_s = search_n(vec1.begin(), vec1.end(), 2, 12);
	auto ptr = search(vec1.begin(), vec1.end(), sub.begin(), sub.end());
	auto ptrEnd = find_end(vec1.begin(), vec1.end(), sub.begin(), sub.end());

7

iter = find_first_of(vec1.begin(), vec1.end(), sub.begin(), sub.end());
iter = find_first_of(vec1.begin(), vec1.end(), sub.begin(), sub.end(),[](int x, int y){return x == y*4;});
iter = a

8、adjacent_find

	vector<int> vec2;
	vec2.push_back(12);
	vec2.push_back(13);
	vec2.push_back(14);
	vec2.push_back(14);
	vec2.push_back(15);
	vec2.push_back(60);
	vec2.push_back(70);
	auto aiter = adjacent_find(vec2.begin(), vec2.end());
	
	auto aaiter = adjacent_find(vec2.begin(), vec2.end(), [](int x, int y) { return y == x * 4; });

9、 comparing range

equal is_permutation

	if (equal(vec1.begin(), vec1.end(), vec2.begin())) {
		cout << " same" << endl;
	}
	if (is_permutation(vec1.begin(), vec1.end(), vec2.begin(),vec2.end())) {
		cout << " have same item, but different order" << endl;
	}

10. mismatch

	/*
	* find first difference
	* pair_iter.first is iterator of vec1 
	* pair_iter.second is iterator of vec2
	*/
	auto pair_iter = mismatch(vec1.begin(), vec1.end(), vec2.begin());

10、

	/*
	* one by one compare item 
	* {1,2,3,4}<{1,2,4,5}
	*/
	bool cp = lexicographical_compare(vec1.begin(), vec1.end(), vec2.begin(),vec2.end());

11、is_sorted is_sorted_until

	bool is_st = is_sorted(vec1.begin(), vec1.end());
	auto is_st_iter = is_sorted_until(vec1.begin(), vec1.end());

12 is_partitioned

//check if vec2 is partitioned by the condition x >10
bool is_par = is_partitioned(vec2.begin(), vec2.end(), [](int x) {return x > 10; });

### 13 is_heap is_heap_until

//check if vec is a heap
is_heap(vec.begin(),vec.end());
auto iter = is_heap_until(vec.begin(),vec.end());

### 14  all_of  any_of  none_of
 
```	bool allb = all_of(vec1.begin(), vec1.end(), [](int x) { return x > 10; });
	bool anyb = any_of(vec1.begin(), vec1.end(), [](int x) { return x > 10; });
	bool noneb = none_of(vec1.begin(), vec1.end(), [](int x) { return x > 10; });