PAT 1054 The Dominant Color （20 分）

1054 The Dominant Color （20 分）

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.

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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, $2^24$). It is guaranteed that the strictly dominant color exists for each input image. All the numbers in a line are separated by a space.

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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

解析

Dominant Color是指出现超过一半的颜色。但是其实只用统计出现次数最多即可。
选择一组元素里出现次数最多的元素。
建立一个map映射，从元素-> 出现次数即可。



Code:

#include<unordered_map>
#include<algorithm>
#include<cstdio>
#include<iostream>
#include<utility>
using namespace std;
int main()
{
	int N, M;
	scanf("%d %d", &N, &M);
	unordered_map<int, int> dominant;
	for (int i = 0; i < M; i++) {
		int input;
		for (int j = 0; j < N; j++) {
			scanf("%d", &input);
			dominant[input]++;
		}
	}
	pair<int, int> max{-1,-1};
	for (auto x : dominant) {
		if (max.second < x.second) {
			max.first = x.first;
			max.second = x.second;
		}
	}
	printf("%d", max.first);
}