1: Implementation with STL

Learning-ACM

C-functions

• cctype
  
  • isalnum, isalpha, isdigit, islower, isupper //bool
  • tolower, toupper //char lowerC = tolower(c);
• cmath
  
  • 三角函数系列，pow, log, etc. // log(x) = $ln x$, log10(x) = $log_{10} x$
  • 浮点数！！ // int x = pow(10, 2) = 99.9999999 = 99
• cstdio
  
  • getchar, putchar, gets, puts 非格式化的 %c
    //10 15
    scanf("%d%d", &x, &y);
    char c[2];
    scanf("%s", c);
    c[0], *c, if(*c == 'Q')
  • scanf, printf 格式化的
  • stdin, stdout
  • sprintf(char* dest, "%2d:%2d", 12, 00) => dest: "12:00"
  • 数字与字符串互转
    
    • atoi // char digit[10] = "10"; int x = atoi(digit);
    • sprintf
• cstring
  
  • strlen(const char* src)
  • strcpy(char* dest, const char* src)
  • strchr(const char*, char c) = char*
    char src[10] = "abcde", char c = 'c';
    char* pos = strch(src, c);
    int posInt = pos - src; // 2
  • strstr(const char* src, const char* pattern) = char*
  • strcmp(const char* lhs, const char* rhs)
    
    • first different char, lhs - rhs, negative, 0, positive
• climits
  
  • 各种类型的最大最小值，平常自己感觉一下就好了
  • char -256 ~ 255 1byte // CHAR_MAX, CHAR_MIN
  • short -3e4 ~ 3e4 2bytes //
  • int -2e9 ~ 2e9 4bytes
  • long long -9e18 ~ 9e18 8bytes
  • float 3e-38 ~ 3e38 精度6~7位 4bytes
  • double 1e-308 ~ 1e308 精度15~16位 8bytes
  • long double windows至少10bytes, linux 16bytes 精度自己感受一下

C++ algorithm

• sort
  sort(begin, end, cmp);
• find
  find(begin, end, x) = iterator //O(n)
• fill
• replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value)
• reverse
• unique //sorted list
• lower_bound, upper_bound //sorted list
• random_shuffle
• merge
• min, max, min_element, max_element
• next_premutation

C++ others

• complex
• functional
  
  • less, greater
• initializer_list (C++11)
• tuple (C++11)

C++ containers

Type

• list, forward_list
• map, set
• queue, stack, deque, priority_queue
• vector
• bitset
• array (c++11)
• unordered_map, unorder_set (c++11)

Usage

• access
  
  • iterator
  • [] operator
• modify
  
  • back, front
  • random

C++ string

• string(const char*), string(n, char)
• insert(positon/iterator, char/string)
• erase(position, len), erase(iterator), erase(begin, end)
• substr(position, len), find(char/string, [position])
• c_str
• string::npos
• operator+
• getline
• stoi,...., to_string (C++ 11)

Suggestions

除非必要，尽量不要手写已有的STL algorithms
不卡时间的情况，尽量使用STL Containters