题目

Behind the scenes in the computer’s memory, color is always talked about as a series of 24 bits of information for each pixel. In an image, the color with the largest proportional area is called the dominant color. A strictly dominant color takes more than half of the total area. Now given an image of resolution M by N (for example, 800×600), you are supposed to point out the strictly dominant color.

Input Specification:

Each input file contains one test case. For each case, the first line contains 2 positive numbers: M (≤800) and N (≤600) which are the resolutions of the image. Then N lines follow, each contains M digital colors in the range [0,224). It is guaranteed that the strictly dominant color exists for each input image. All the numbers in a line are separated by a space.

Output Specification:

For each test case, simply print the dominant color in a line.

Sample Input:

1
2
3
4

5 3
0 0 255 16777215 24
24 24 0 0 24
24 0 24 24 24

Sample Output:

1

24

题解

思路

• 题目意思就是给你一堆数据，让你找到出现次数大于总数一半的
• 很显然用哈希表来存储每个点的出现频次
• 这是传统的方法
• 在Python里统计频次有专门的Counter，也一并附上代码，使用它非常方便。

数据结构

• _dict 是一个哈希表
  • 键是题目里的颜色
  • 值是出现次数

算法

• 就哈希表呗

代码

• 因为使用Python能AC，所以只放了Python的代码。

Python3 defaultdict

1
2
3
4
5
6
7
8
9
10
11
12

from collections import defaultdict

M, N = list(map(int, input().split()))
half = M * N // 2
_dict = defaultdict(int)
for _ in range(N):
    for i in input().split():
        _dict[i] += 1
        if _dict[i] > half:
            print(i)
            break

Python3 counter

1
2
3
4
5
6
7
8

from collections import Counter

M, N = list(map(int, input().split()))
ans = Counter()
for _ in range(N):
    ans.update(input().split())
print(ans.most_common(1)[0][0])