1054 The Dominant Color

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:

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

Sample Output:

24

给定一个二维数组，指定屏幕中所有颜色，找出出现次数过半的颜色。

思路

具体思路如下：

1. 用一个哈希表来存储每个颜色出现的次数。
2. 找出出现此处过半的颜色并输出。

代码

#include<bits/stdc++.h>
using namespace std;
unordered_map<string, int> cnt;
int n, m;
int main()
{
    //输入屏幕的颜色并记录每个颜色出现的次数
    cin >> n >> m;
    for (int i = 0; i < n * m; i++)
    {
        string x;
        cin >> x;
        //如果已经找到则直接break
        if (++cnt[x] > n * m / 2)
        {
            cout << x << endl;
            break;
        }
    }
    return 0;
}