update state (i,a,b,s). foot f is moved to t

cost accumulated when walking from x1 and x2. section[i~j] are already finished

查找给定集合x的ID。如果找不到，分配一个新ID

compare average of x1~x2 and x3~x4

returns the output of input 000..0111...1 (there are k 0's)

initialize pa and sort e before calling this method cnt is the current number of components

输入并统计一棵子树，树根水平位置为p

how many red balloons after k hours

now we received i zeros and j ones. Can we receive another zero at the next time?

把第p堆高度为h的木块上方的所有木块移回原位

how many red balloons in the first i rows, after k hours

how many times digit d occurred in 0~n-1 numbers in 0~4567 can be divided into the following patterns: fewer digits : *, n*, n** (n means non-zero d

increased height if you place a book with height h to a level with width w if w == 0, that means the level if empty, so height is increased by h other

找木块a所在的pile和height，以引用的形式返回调用者

翻转a[0..p]

返回满足1/c <= a/b的最小c

逆时针走t步，步长是d（-1表示顺时针走），返回新位置

number of matches in a full n*n grid

输出字符串s，长度不足len时补字符extra