1856-More is better-基础并查集

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思路：注意n为0的时候输出1，还有内存。这题是数据水了，要不我的Count[ ]数组，开10^5绝对会WA。离散化还没想清楚，想清楚了再更新代码。【水过代码下面是正经的AC代码，其实这道题不用离散化，因为即使离散化还是要开多两个10^7的数组，之前就是因为酱紫MLE了，后来只是改变了路径压缩的方式，把原本的记录高度改成记录树里的节点数，道理是一样的，不会退化。还省了点内存。】

下面是水过的AC代码：

#include<iostream>#include<cstdio>#include<vector>#include<cstring>#include<algorithm>using namespace std;#define maxn 10000009int par[maxn], h[maxn], n, Count[maxn/100];bool vis[maxn];void init(){  for(int i = 0; i < maxn; i++) {    par[i] = i;    vis[i] = false;    h[i] = 0;    if(i < maxn/100)     Count[i] = 0;  }}bool cmp(int a, int b){  return a > b;}int Find(int x){  if(par[x] == x) return x;  return par[x] = Find(par[x]);}void Union(int a, int b){  a = Find(a);  b = Find(b);  if(h[a] > h[b]) par[b] = par[a];  else{    if(h[a] == h[b]) h[b]++;    par[a] = par[b];  }}void work(){  for(int i = 0; i < n; i++){     int a, b;     scanf("%d%d", &a, &b);     Union(a, b);     vis[a] = vis[b] = true;  }  for(int i = 0; i < maxn; i++)    if(vis[i]) {      int p = Find(i);      Count[p]++;    }  sort(Count,Count+maxn/100,cmp);  cout<<Count[0]<<endl;}int main(){  while(scanf("%d", &n) != EOF){    if(n != 0){     init();     work();    }    else cout<<"1"<<endl;  }  return 0;}

AC代码II：

//AC#include<iostream>#include<cstdio>#include<vector>#include<cstring>#include<algorithm>using namespace std;#define maxn 10000009int par[maxn],child_num[maxn], Max, n;void init(){  for(int i = 0; i < maxn; i++) {    par[i] = i;    child_num[i] = 1;  }  Max = 0;}int Find(int x){  if(par[x] == x) return x;  return par[x] = Find(par[x]);}void Union(int a, int b){  a = Find(a);  b = Find(b);  if(a != b)     if(child_num[a] > child_num[b]) {       par[b] = par[a];       child_num[a] += child_num[b];       if(Max < child_num[a]) Max = child_num[a];     }     else{       child_num[b] += child_num[a];       par[a] = par[b];       if(Max < child_num[b]) Max = child_num[b];     }}void work(){  for(int i = 0; i < n; i++){     int a, b;     scanf("%d%d", &a, &b);     Union(a, b);  }  cout<<Max<<endl;}int main(){  while(scanf("%d", &n) != EOF){    if(n != 0){     init();     work();    }    else cout<<"1"<<endl;  }  return 0;}

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