流利说：笔试题（20190911）

礼物派发

动态规划的思想。考虑三种可能，左边没有右边有，左边有右边没有，左边有和右边有。其中左边有和右边有则分两种情况，即加入左边或者加入右边。

def send_gift(n, a, b, seq):
    if n == 0:
        return 0
    if not seq:
        return 0
    left, right = seq[0]
    first, second, third = float('inf'), float('inf'), float('inf')
    # print(left, right, a, b)
    if a < 1 and b > 0:
        first = right + send_gift(n - 1, a, b - 1, seq[1:])
    if b < 1 and a > 0:
        second = left+send_gift(n-1, a-1, b, seq[1:])
    if a > 0 and b > 0:
        third = min(left+send_gift(n-1, a-1, b, seq[1:]),
                   right + send_gift(n - 1, a, b - 1, seq[1:]))
    return min(first, second, third)


if __name__ == '__main__':
    n = int(input().strip())
    a, b = list(map(int, input().strip().split()))
    seq = []
    for _ in range(n):
        cur = list(map(int, input().strip().split()))
        seq.append(cur)
    res = send_gift(n, a, b, seq)
    print(res)


'''
3
1 2
13 19
4 9
10 20
'''

猫捉老鼠

典型的一道广度优先遍历的题目。先找到起点，设置一个双端队列，每一次都往外递增一层，直到找到最终的结果，即目标值等于3的位置。

import sys
from collections import deque


def cat_catch_mouse(seq):
    if not seq:
        return 0
    row, col = len(seq), len(seq[0])
    start = find_point(seq, row, col)
    container = deque()
    container.append([start])
    res = -1
    while container:
        value = container.popleft()
        res += 1
        current = set()
        # print(container, value, res)
        for vu in value:
            r, c = vu
            if seq[r][c] == 3:
                return res
            if r-1 >= 0 and seq[r-1][c] != 1:
                current.add((r-1, c))
            if r+1 < row and seq[r+1][c] != 1:
                current.add((r+1, c))
            if c-1 >= 0 and seq[r][c-1] != 1:
                current.add((r, c-1))
            if c+1 < col and seq[r][c+1] != 1:
                current.add((r, c+1))
        container.append(list(current))


def find_point(seq, row, col):
    for si in range(row):
        for sj in range(col):
            if seq[si][sj] == 2:
                return (si, sj)


if __name__ == '__main__':
    seq = []
    for line in sys.stdin:
        seq.append(list(map(int, line.strip().split())))
    res = cat_catch_mouse(seq)
    print(res)

'''
2 0 0 1
0 1 0 1
1 0 0 0
3 0 1 0
'''

（最近更新：2019年09月14日）