Stones on the Table

time limit per test2 seconds
memory limit per test256 megabytes
inputstandard input
outputstandard output
There are n stones on the table in a row, each of them can be red, green or blue. Count the minimum number of stones to take from the table so that any two neighboring stones had different colors. Stones in a row are considered neighboring if there are no other stones between them.

Input
The first line contains integer n (1 ≤ n ≤ 50) — the number of stones on the table.

The next line contains string s, which represents the colors of the stones. We’ll consider the stones in the row numbered from 1 to n from left to right. Then the i-th character s equals “R”, if the i-th stone is red, “G”, if it’s green and “B”, if it’s blue.

Output
Print a single integer — the answer to the problem.

Examples
inputCopy
3
RRG
outputCopy
1
inputCopy
5
RRRRR
outputCopy
4
inputCopy
4
BRBG
outputCopy
0

問題簡述：

  給出一個字串，由"B",“R”,"G"組成，分別代表藍色石頭，紅色石頭，綠色石頭，從中去掉幾塊石頭才能使得相鄰石頭顏色不一樣？

問題分析：

  對字串做處理，將相鄰的相同字元只保留一個，統計去掉的字元數。

程式說明：

  從頭開始遍歷字串，若當前字元與下一個相同，去掉下一個，統計去掉的數量。

程式實現：

#include<iostream>
#include<string>
using namespace std;

int main()
{
    int n,sum=0;
    string str;
    cin>>n>>str;
    for(int i=0;i<str.size()-1;i++)
    {
        if(str[i]==str[i+1])
        {
            str.erase(i+1,1);
            i--;
            sum++;
        }
    }
    cout<<sum;
}