HDOJ 1856 More is better (并查集 + 压缩路径 + 结点深度)

More is better

                                                                   Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 327680/102400 K (Java/Others)
                                                                                             Total Submission(s): 28896    Accepted Submission(s): 10270


Problem Description
Mr Wang wants some boys to help him with a project. Because the project is rather complex,  the more boys come, the better it will be. Of course there are certain requirements.

Mr Wang selected a room big enough to hold the boys. The boy who are not been chosen has to leave the room immediately. There are 10000000 boys in the room numbered from 1 to 10000000 at the very beginning. After Mr Wang's selection any two of them who are still in this room should be friends (direct or indirect), or there is only one boy left. Given all the direct friend-pairs, you should decide the best way.
 

Input
The first line of the input contains an integer n (0 ≤ n ≤ 100 000) - the number of direct friend-pairs. The following n lines each contains a pair of numbers A and B separated by a single space that suggests A and B are direct friends. (A ≠ B, 1 ≤ A, B ≤ 10000000)
 

Output
The output in one line contains exactly one integer equals to the maximum number of boys Mr Wang may keep. 
 

Sample Input
 
   
4 1 2 3 4 5 6 1 6 4 1 2 3 4 5 6 7 8
 

Sample Output
 
   
4 2
Hint
A and B are friends(direct or indirect), B and C are friends(direct or indirect), then A and C are also friends(indirect). In the first sample {1,2,5,6} is the result. In the second sample {1,2},{3,4},{5,6},{7,8} are four kinds of answers.
 

Author
lxlcrystal@TJU
 

Source
HDU 2007 Programming Contest - Final
 

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题意:两两之间是朋友,求最大朋友圈有多少人。

坑点:n = 0 时,输出要为1。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define inf 0x3f3f3f3f
#define PI 3.14159265358979323
#define SCD(a) scanf("%d",&a)
#define SCDD(a,b) scanf("%d%d",&a,&b)
#define SCF(a) scanf("%lf",&a)
#define PTD(a) printf("%d\n",a)
#define PTS(a) printf("%s\n",a)
#define MST(a) memset(a, 0, sizeof(a))
using namespace std;
//                      HDOJ 1856

const int L = 10000001;

int f[L];
int depth[L];
int n, m;
int ans;

void init()
{
    int i;
    for(i=1;i<=10000000;i++){
        f[i] = i;
        depth[i] = 1;
    }
    ans = 1;    //WA后看了题解,这个初值要为1,n==0时 要输出1,坑啊,╭(╯^╰)╮
}

int fid(int x)
{
    int r = x;
    int t;
    while( r != f[r] )
        r = f[r];
    while(x != r){  //路径压缩
        t = f[x];
        f[x] = r;
        x = t;
    }
    return r;
}

void combine(int a, int b)
{
    int fa;
    int fb;
    fa = fid(a);
    fb = fid(b);
    if(fa != fb){
        f[fa] = fb;
        depth[fb] += depth[fa];     //结点深度
        ans = max(ans, depth[fb]);
    }
}

int main()
{
    int i ,j ,a ,b ,t, x, y;
    while(~SCD(n)){
        init();
        for(i=0;i



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