树链剖分模版

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 10010;struct edge{int v, next;}e[maxn*2];int first[maxn], cnt;int top[maxn], dep[maxn], sz[maxn], f[maxn], son[maxn], rank[maxn], tid[maxn];int tp, tim;int d[maxn][3];int n;void AddEdge(int u, int v){e[cnt].v = v;e[cnt].next = first[u];first[u] = cnt++;e[cnt].v = u;e[cnt].next = first[v];first[v] = cnt++;}void init(){memset(first, -1, sizeof(first));cnt = 1;memset(son, -1, sizeof(son));tim = 0;}void dfs1(int u, int fa, int d){sz[u] = 1;dep[u] = d;f[u] = fa;for(int i = first[u]; i != -1; i = e[i].next){int v = e[i].v;if(v == fa)continue;dfs1(v, u, d+1);sz[u] += sz[v];if(son[u] == -1 || sz[son[u]] < sz[v])son[u] = v;}}void dfs2(int u, int tp){top[u] = tp;tid[u] = ++tim;rank[tid[u]] = u;if(son[u] == -1)return;dfs2(son[u], tp);for(int i = first[u]; i != -1; i = e[i].next){int v = e[i].v;if(v != f[u] && son[u] != v)dfs2(v, v);}}int ma[maxn<<2];int mi[maxn<<2];int lz[maxn<<2];void pushup(int l, int r, int rt){ma[rt] = max(ma[rt<<1], ma[rt<<1|1]);mi[rt] = min(mi[rt<<1], mi[rt<<1|1]);}void build(int l, int r, int rt){ma[rt] = 0;mi[rt] = 0;lz[rt] = 0;if(l == r){return;}int m = (l + r) >> 1;build(l, m, rt<<1);build(m+1, r, rt<<1|1);}void pushdown(int l, int r, int rt){if(l == r)return;if(lz[rt]){mi[rt<<1] = -mi[rt<<1];ma[rt<<1] = -ma[rt<<1];swap(mi[rt<<1], ma[rt<<1]);mi[rt<<1|1] = -mi[rt<<1|1];ma[rt<<1|1] = -ma[rt<<1|1];swap(mi[rt<<1|1], ma[rt<<1|1]);lz[rt<<1] ^= 1;lz[rt<<1|1] ^= 1;lz[rt] = 0;}}void update(int x, int y, int l, int r, int rt){if(x == l && y == r){mi[rt] = -mi[rt];ma[rt] = -ma[rt];swap(mi[rt], ma[rt]);lz[rt] ^= 1;return;}pushdown(l, r, rt);int m = (l + r) >> 1;if(y <= m)update(x, y, l, m, rt<<1);else if(x > m)update(x, y, m+1, r, rt<<1|1);else{update(x, m, l, m, rt<<1);update(m+1, y, m+1, r, rt<<1|1);}pushup(l, r, rt);}void update2(int x, int l, int r, int rt, int w){if(l == r){ma[rt] = mi[rt] = w;lz[rt] = 0;return;}pushdown(l, r, rt);int m = (l + r) >> 1;if(x <= m)update2(x, l, m, rt<<1, w);elseupdate2(x, m+1, r, rt<<1|1, w);pushup(l, r, rt);}int query(int x, int y, int l, int r, int rt){if(l == x && r == y)return ma[rt];pushdown(l, r, rt);int m = (l + r) >> 1;if(y <= m)return query(x, y, l, m, rt<<1);else if(x > m)return query(x, y, m+1, r, rt<<1|1);else{return max(query(x, m, l, m, rt<<1), query(m+1, y, m+1, r, rt<<1|1));}}void change(int u, int v){while(top[u] != top[v]){if(dep[top[u]] < dep[top[v]])swap(u, v);update(tid[top[u]], tid[u], 1, n, 1);u = f[top[u]];}if(u == v)return;if(dep[u] > dep[v])swap(u, v);update(tid[son[u]], tid[v], 1, n, 1);}int find(int u, int v){int ans = -999999999;while(top[u] != top[v]){if(dep[top[u]] < dep[top[v]])swap(u, v);ans = max(ans, query(tid[top[u]], tid[u], 1, n, 1));u = f[top[u]];}if(u == v)return ans;if(dep[u] > dep[v])swap(u, v);ans = max(ans, query(tid[son[u]], tid[v], 1, n, 1));return ans;}int main(){int T;scanf("%d", &T);while(T--){init();scanf("%d", &n);for(int i = 1; i < n; i++){int u, v, w;scanf("%d %d %d", &u, &v, &w);AddEdge(u, v);d[i][0] = u;d[i][1] = v;d[i][2] = w;}dfs1(1, 0, 0);dfs2(1, 1);build(1, n, 1);for(int i = 1; i < n; i++){if(dep[d[i][0]] > dep[d[i][1]])swap(d[i][0], d[i][1]);update2(tid[d[i][1]], 1, n, 1, d[i][2]);}char s[10];while(scanf("%s", s) && strcmp(s, "DONE")){if(s[0] == 'Q'){int x, y;scanf("%d %d", &x, &y);printf("%d\n", find(x, y));}else if(s[0] == 'C'){int x, y;scanf("%d %d", &x, &y);update2(tid[d[x][1]], 1, n, 1, y);}else{int x, y;scanf("%d %d", &x, &y);change(x, y);}}} return 0;}