AtCoder Grand Contest #026 A - Colorful Slimes 2

Time Limit: 2 sec / Memory Limit: 1024 MB

Score : 200200 points

Problem Statement

Takahashi lives in another world. There are slimes (creatures) of 1000010000 colors in this world. Let us call these colors Color 1,2,...,100001,2,...,10000.

Takahashi has NN slimes, and they are standing in a row from left to right. The color of the ii-th slime from the left is aiai. If two slimes of the same color are adjacent, they will start to combine themselves. Because Takahashi likes smaller slimes, he has decided to change the colors of some of the slimes with his magic.

Takahashi can change the color of one slime to any of the 1000010000 colors by one spell. How many spells are required so that no slimes will start to combine themselves?

Constraints

• 2≤N≤1002≤N≤100
• 1≤ai≤N1≤ai≤N
• All values in input are integers.

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Input

Input is given from Standard Input in the following format:

NN
a1a1 a2a2 ...... aNaN

Output

Print the minimum number of spells required.

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Sample Input 1 Copy

Copy

5
1 1 2 2 2

Sample Output 1 Copy

Copy

2

For example, if we change the color of the second slime from the left to 44, and the color of the fourth slime to 55, the colors of the slimes will be 1,4,2,5,21,4,2,5,2, which satisfy the condition.

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Sample Input 2 Copy

Copy

3
1 2 1

Sample Output 2 Copy

Copy

0

Although the colors of the first and third slimes are the same, they are not adjacent, so no spell is required.

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Sample Input 3 Copy

Copy

5
1 1 1 1 1

Sample Output 3 Copy

Copy

2

For example, if we change the colors of the second and fourth slimes from the left to 22, the colors of the slimes will be 1,2,1,2,11,2,1,2,1, which satisfy the condition.

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Sample Input 4 Copy

Copy

14
1 2 2 3 3 3 4 4 4 4 1 2 3 4

Sample Output 4 Copy

Copy

4

对于连续相同的只需要把一半的换颜色就可以了。
代码：

import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int a = 0;
        int b = 0;
        int c = 0;
        int ans = 0;
        for(int i = 0;i < n;i ++) {
            b = in.nextInt();
            if(a == b)c ++;
            else {
                ans += c / 2;
                c = 1;
            }
            a = b;
        }
        ans += c / 2;
        System.out.println(ans);
    }

}