HDU3038 坑爹的并查集 还是有点难的 加权并查集

悲剧的我总之会忘记去初始化一些东西  这次就是忘了初始化  ans#include<stdio.h>int f[200010],sum[200010];int ans = 0;int n;int find(int x){    if (f[x] == x) return x;        int t = f[x];        f[x] = find(f[x]);        sum[x] += sum[t];        return f[x];} int merge(int x,int y,int c){    int a = find(x);    int b = find(y);    if (a == b)    {        if(sum[y] != sum[x] + c)        ans++;        return 0;    }    if(a > b)    {        sum[a] = sum[y]-sum[x] - c;        f[a] = b;    }    else     {        sum[b] = sum[x] - sum[y] + c;        f[b] = a;    }    return 0;}void init(){    int i;    ans = 0;    for (i = 0 ;i <= n ;i++)    {        f[i] = i;        sum[i] = 0;    }   }int main(){    int m;    int a,b,c;    while(scanf("%d%d",&n,&m)!=EOF)    {            init();            while(m--)    {        scanf("%d%d%d",&a,&b,&c);        merge(a - 1,b,c);    }    printf("%d\n",ans);    }    return 0;}这是第二遍打的  差不了多少的#include<stdio.h>int c,n,m,i,ans;int father[200010],sum[200010];int find(int x){    if(x == father[x] )    return x;    int t = father[x];    father[x] = find(father[x]);    sum[x] += sum[t];    return father[x];}int merge(int x,int y){    int a = find(x);    int b = find(y);    if(a == b)    {        if(sum[x] != sum[y] - c)        ans++;        return 0;    }    if(a > b)    {        sum[a] = sum[y] - sum[x] - c;        father[a] = b;    }    if(b > a)    {        sum[b] = sum[x] - sum[y] + c;        father[b] = a;    }    return 0;}void init(){    ans = 0;    for(i = 0;i <= n ;i++ )    {        sum[i] = 0;        father[i] = i;    }}int main(){    int a,b;    while(scanf("%d%d",&n,&m)!=EOF)    {        init();        while(m--)        {                scanf("%d%d%d",&a,&b,&c);                merge(a-1,b);        }        printf("%d\n",ans);    }    return 0;}第三遍的修改  其实  根本就不需要  规定  从大到小  还是  从小到大  为  root#include<stdio.h>int c,n,m,i,ans;int father[200010],sum[200010];int find(int x){    if(x == father[x] )    return x;    int t = father[x];    father[x] = find(father[x]);    sum[x] += sum[t];    return father[x];}int merge(int x,int y){    int a = find(x);    int b = find(y);    if(a == b)    {        if(sum[x] != sum[y] - c)        ans++;        return 0;    }//  if(a > b)//  {        sum[a] = sum[y] - sum[x] - c;        father[a] = b;//  }                                                                 就是这里  其实根本没有 要求严格//  if(b > a)//  {                                                                其实  仔细想一想  应该是 测试数据 太渣了  才可以 ac吧           这样不去指定 一个方向  还是很伤的吧         恩  应该就是这样没错          在更新的时候，数值小的一定是为根节点，//      sum[b] = sum[x] - sum[y] + c;//      father[b] = a;//  }    return 0;}void init(){    ans = 0;    for(i = 0;i <= n ;i++ )    {        sum[i] = 0;        father[i] = i;    }}int main(){    int a,b;    while(scanf("%d%d",&n,&m)!=EOF)    {        init();        while(m--)        {                scanf("%d%d%d",&a,&b,&c);                merge(a-1,b);        }        printf("%d\n",ans);    }    return 0;}