A1054 The Dominant Color 难度2

1. 题目描述

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,). 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

2. 问题分析

• 遍历这个图片，看哪个像素个数最多，可以使用hash数组（因为范围很大）或者map

• 然后遍历map，找到最大的像素的key 即为dominat color

• 如何读取M个数？scanf()循环就可以

3. 代码

#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <unordered_map>
#include <cstring>
#include <unordered_set>
#include <sstream>

using namespace std;


int main() {
    int M,N;
    map<long,int >mp;
    long color;
    scanf("%d %d",&M,&N);
    for(int i=0;i<N;i++)
    {
        for(int j=0;j<M;j++)
        {
            scanf("%ld",&color);
            mp[color]++;
        }
    }

    int maxcolornum = -1;
    long maxcolor = -1;
    for(auto it:mp)
    {
       if(it.second>maxcolornum)
       {
           maxcolornum = it.second;
           maxcolor = it.first;
       }
    }
    printf("%ld",maxcolor);
}

4. 思考与收获

• 注意使用long

• 要获取最大值所在的key，不能使用max，max只能获取最大值