POJ1470 Closest Common Ancestors（LCA入门）

LCA裸题，读入比较毒瘤

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=1e5;
int N;
int head[maxn];
int tol;
struct node {
    int u;
    int v;
    int next;
}edge[maxn]; 
void addedge (int u,int v) {
    edge[tol].u=u;
    edge[tol].v=v;
    edge[tol].next=head[u];
    head[u]=tol++;
}

int h[maxn];
int father[20][maxn];
int isRoot[maxn];
void dfs (int x) {
    for (int i=head[x];i!=-1;i=edge[i].next) {
        int v=edge[i].v;
        if (v==father[0][x]) continue;
        father[0][v]=x;
        h[v]=h[x]+1;
        dfs(v);
    }
}
int lca (int x,int y) {
    if (h[x]<h[y]) swap(x,y);
    for (int i=17;i>=0;i--) 
        if (h[x]-h[y]>>i) x=father[i][x];
    if (x==y) return x;
    for (int i=17;i>=0;i--) {
        if (father[i][x]!=father[i][y]) {
            x=father[i][x];
            y=father[i][y];
        }
    }
    return father[0][x];
}

int main () {
    while (~scanf("%d",&N)) {
        memset(head,-1,sizeof(head));
        memset(isRoot,0,sizeof(isRoot));
        tol=0;
        memset(h,0,sizeof(h));
        memset(father,0,sizeof(father));
        for (int i=0;i<N;i++) {
            int x,k;
            scanf("%d:(%d)",&x,&k);
            for (int j=0;j<k;j++) {
                int y;
                scanf(" %d",&y);
                addedge(x,y);
                addedge(y,x);
                isRoot[y]=1;
            }
        }
        int root;
        for (root=1;root<=N;root++)
            if (!isRoot[root]) break;
        dfs(root);
        for (int i=1;i<=17;i++)
            for (int j=1;j<=N;j++) 
                father[i][j]=father[i-1][father[i-1][j]];
        int q;
        memset(isRoot,0,sizeof(isRoot));
        scanf("%d",&q);
        for (int i=0;i<q;i++) {
            int x,y;
            scanf(" (%d %d)",&x,&y);
            isRoot[lca(x,y)]++;
        }
        for (int i=1;i<=N;i++) 
            if (isRoot[i]) printf("%d:%d
",i,isRoot[i]);
    }
    return 0;
}