SRM 595 DIV 1

逻辑分析题，注意以下关键性质：

一个球被染成什么颜色取决于最后一次的染色情况，如果没有被染过色，那么默认是白色

结果总是的2的乘方

class LittleElephantAndIntervalsDiv1:
    def getNumber(self, m, l, r):
        # the last color
        a = [-1] * m
        for rou in range(0, len(l)):
            for i in range(l[rou]-1, r[rou]):
                a[i] = rou
                
        # count key round
        s = set(a)
        
        # calc
        tot = 2 ** (len(s) - (1 if -1 in s else 0))
        return tot
    
    
    
# test 
o = LittleElephantAndIntervalsDiv1()

# test case
assert(o.getNumber(4, (1,2,3), (1,2,3)) == 8)
assert(o.getNumber(3, (1,1,2), (3,1,3)) == 4)
print('ok')