Submission #83589

#	Time	Username	Problem	Language	Result	Execution time	Memory
83589		XBXJLeiLeLeiLe	Mate (COCI18_mate)	Cpython 2	0 / 100	24 ms	4068 KiB

mate

s = raw_input()
q = input()


def combination(n, d):
    k = d - 2
    if n - k < k:
        k = n - k
    result = 1
    for i in range(k):
        result *= n
        n -= 1
    for i in range(k):
        result /= k
        k -= 1
    return result


def mod(num):
    return num % (10**9+7)


def lst_id(letter):
    return ord(letter) - ord("a")

arr = [[0 for i in range(26)] for i in range(len(s))]

arr_c = [0] * 26
for i in range(len(s)-1, -1, -1):
    for j in range(26):
        arr[i][j] = arr_c[j]
    arr_c[lst_id(s[i])] += 1


arr_r = []
for i in range(q):
    d, xy = raw_input().split()
    total = 0
    d = int(d)
    x = xy[0]
    y = xy[1]
    for i in range(len(s)):
        if s[i] == x and i >= d - 2:
            total += mod(combination(i, d) * arr[i][lst_id(y)])
    arr_r.append(mod(total))

for i in arr_r:
    print i

• Subtask 1: 0 / 100