zcmu-1279 Sort photos（仔细读题）

最新推荐文章于 2020-01-02 15:35:28 发布

原创最新推荐文章于 2020-01-02 15:35:28 发布 · 577 阅读

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本文介绍了一个有趣的算法问题：如何通过最少的操作将一堆照片全部翻转到同一面。问题设定为给定一组面向上或下的照片，只能翻转方向一致的照片，目标是最小化翻转次数。文章提供了一个C++实现的示例，展示了如何通过比较连续不同方向照片的数量来找到最小翻转数。

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Description

Imagine you have a pile of n photos. Some of them are faced upwards and the others faced downwards. Your goal is to sort them so that all the photos are faced the same direction. The only operation you are allowed to do is to take any amount of the photos if their direction is same to the other direction. Write the program that calculates the minimum number of such operations needed to complete the sorting goal.

Input

There are multiple test cases in the input file.
For each test case, the first line is n (0<n<10^5) - the number of photos.
The second line is n characters "D" - faced down or "U" - faced up.

Output

For each test case there is a single integer number - minimal number of flip operations required to sort the photos pile.

Sample Input

5

UUDUU

4

UDUD

Sample Output

1

2

仔细读红字部分

#include <cstdio>
#include <iostream>
#include <cstring>
using namespace std;

int main() {
    int n;
    char str[100005];
    while(scanf("%d",&n)!=EOF)
    {
        int x = 0,y = 0;
        scanf("%s",str);
        int len = strlen(str);
        for(int i = 0; i < len;i++)
        {
            if(str[i] == 'U' && str[i + 1] != 'U')
                x ++;
            if(str[i] == 'D' && str[i + 1] != 'D')
                y ++;
        }
        printf("%d\n",min(x,y));
    }
    return 0;
}