P2420 让我们异或吧

树链剖分

#include <algorithm>
#include <cstdio>
#include <vector>
using namespace std;
const int maxn = 100000 + 10;
int n,m,r,p,dis[maxn],dep[maxn],father[maxn][18];
vector<pair<int,int> > edges[maxn];
inline void dfs(int now,int f,int Xor) {  //dfs预处理
    dis[now] = Xor;
    for (size_t i = 0;i < edges[now].size();i++)
        if (edges[now][i].first != f) {
            dep[edges[now][i].first] = dep[now]+1;
            father[edges[now][i].first][0] = now;
            dfs(edges[now][i].first,now,Xor^edges[now][i].second);
        }
}
inline void init() {  //倍增
    for (int j = 1;j < 18;j++)
        for (int i = 1;i <= n;i++) father[i][j] = father[father[i][j-1]][j-1];
}
inline int lca(int a,int b) {  //求lca
    if (dep[a] < dep[b]) swap(a,b);
    for (int i = 0;i < 18;i++)
        if ((1<<i)&dep[a]-dep[b]) a = father[a][i];  //让深的点往上走
    if (a == b) return a;  //走到同一点
    for (int i = 18;i >= 0;i--)
        if (father[a][i] != father[b][i]) {  //两个一起往上走
            a = father[a][i];
            b = father[b][i];
        }
    return father[a][0];
}
int main() {
    scanf("%d",&n);
    for (int i = 1,u,v,w;i < n;i++) {
        scanf("%d%d%d",&u,&v,&w);
        edges[u].push_back(make_pair(v,w));
        edges[v].push_back(make_pair(u,w));
    }
    dfs(1,1,1);
    init();
    scanf("%d",&m);
    for (int i = 1,u,v;i <= m;i++) {
        scanf("%d%d",&u,&v);
        int tmp = lca(u,v);
        printf("%d
",(dis[u]^dis[tmp])^(dis[v]^dis[tmp]));
    }
    return 0;
}

#include <algorithm>#include <cstdio>#include <vector>usingnamespacestd; constint maxn = 100000 + 10; int n,m,r,p,dis[maxn],dep[maxn],father[maxn][18]; vector<pair<int,int> > edges[maxn]; inline void dfs(int now,int f,int Xor) { //dfs预处理 dis[now] = Xor; for (size_t i = 0;i < edges[now].size();i++) if (edges[now][i].first != f) { dep[edges[now][i].first] = dep[now]+1; father[edges[now][i].first][0] = now; dfs(edges[now][i].first,now,Xor^edges[now][i].second); } } inline void init() { //倍增for (int j = 1;j < 18;j++) for (int i = 1;i <= n;i++) father[i][j] = father[father[i][j-1]][j-1]; } inline int lca(int a,int b) { //求lcaif (dep[a] < dep[b]) swap(a,b); for (int i = 0;i < 18;i++) if ((1<<i)&dep[a]-dep[b]) a = father[a][i]; //让深的点往上走if (a == b) return a; //走到同一点for (int i = 18;i >= 0;i--) if (father[a][i] != father[b][i]) { //两个一起往上走 a = father[a][i]; b = father[b][i]; } return father[a][0]; } int main() { scanf("%d",&n); for (int i = 1,u,v,w;i < n;i++) { scanf("%d%d%d",&u,&v,&w); edges[u].push_back(make_pair(v,w)); edges[v].push_back(make_pair(u,w)); } dfs(1,1,1); init(); scanf("%d",&m); for (int i = 1,u,v;i <= m;i++) { scanf("%d%d",&u,&v); int tmp = lca(u,v); printf("%d ",(dis[u]^dis[tmp])^(dis[v]^dis[tmp])); } return0; }