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.

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.

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

超时版本

#include <iostream>
using namespace std;
// time out edition
int main()
{
    int wid,hei;
    int n[480000];
    int cnt[480000];
    cin >> wid >> hei;
    int num = wid*hei;
    int half = num/2;
    for(int i=0;i<num;i++)
    {
        int tem;
        scanf("%d",&tem);
        n[i] = tem;
        for(int j=0;j<i;j++)
        {
            if(n[i]==n[j]) {
                cnt[i]++;
            }
        }
        if(cnt[i]>=half) {
            cout << n[i];
            return 0;
        }
    }
}

正确版本

#include <iostream>
#include <map>
using namespace std;
int main()
{
    map<int, int> m;
    int wid,hei;
    cin >> wid >> hei;
    int num = wid*hei;
    int half = num/2;
    for(int i=0;i<num;i++)
    {
        int tem;
        scanf("%d",&tem);
        m[tem]++;
        if(m[tem]>half) {
            cout << tem;
            return 0;
        }
    }
}

note:
c++的map和python的dict一样好用，key-value的统计的时候一定要想到。
scanf的速度要比 cin 快好多，超时的时候要考虑替换，一开始就应该scanf