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])