Epidemic in Monstropolis

Epidemic in Monstropolis

题目链接：http://codeforces.com/contest/733/problem/C

贪心

新序列的m个数肯定是由原序列的连续的m个子序列构成的，只需要找到每个连续子序列中最大的数即可。

细节中需要注意：一个连续子序列可能有很多个最大数，最大数的左右两个数必须要有一个小于这个数；还有下标的处理。

代码如下：

 import sys

 n = int(input())
 a = [int(x) for x in input().split()]
 m = int(input())
 b = [int(x) for x in input().split()]

 sum1,sum2 = 0,0
 for i in a:
     sum1 += i
 for i in b:
     sum2 += i

 if sum1 != sum2:
     print('NO')
     sys.exit(0)

 s = []
 idx = 0
 for i in range(m):
     t = b[i]
     oo = idx
     mm = idx

     while t > 0:
         t -= a[idx]
         if a[mm] < a[idx]:
             mm = idx
         idx += 1
     if t < 0:
         print('NO')
         sys.exit(0)

     if mm == oo:
         while mm+1<idx and a[mm]==a[mm+1]:
             mm = mm+1

     flag = 0
     if mm-1>=oo and a[mm]>a[mm-1]:
         flag = 1
     elif mm+1<idx and a[mm]>a[mm+1]:
         flag = 2
     elif idx-oo == 1:
         continue

     if flag == 0:
         print('NO')
         sys.exit(0)
     elif flag == 1:
         for x in range(mm,oo,-1):
             s.append([x-oo+i,'L'])
         for x in range(mm,idx-1):
             s.append([i,'R'])
     elif flag == 2:
         for x in range(mm,idx-1):
             s.append([mm-oo+i,'R'])
         for x in range(mm,oo,-1):
             s.append([x-oo+i,'L'])

 print('YES')
 for x in s:
     print(x[0]+1,x[1])