Poj 3237 TREE tree chain partitioning

Single-point replacement: the opposite number is used for the interval, and the maximum value is used for the interval. In fact, you only need to save the minimum and maximum values in the line segment tree. After the inverse value is used, the minimum value is changed to the maximum value to the minimum value.

#include <cstdio>#include <cstring>#include <algorithm>#include <map>#include <set>#include <bitset>#include <queue>#include <stack>#include <string>#include <iostream>#include <cmath>#include <climits>using namespace std;const int maxn = 10000 + 5;int n, head[maxn], nxt[maxn << 1], u[maxn << 1], v[maxn << 1], w[maxn << 1];int tid[maxn], maxson[maxn], fa[maxn], dep[maxn], siz[maxn], idcnt, ecnt;int top[maxn], maxv[maxn << 2], minv[maxn << 2], sval[maxn], lazy[maxn << 2];int eid[maxn << 1], rnum[maxn];#define lson rt << 1, l, mid#define rson rt << 1 | 1, mid + 1, rvoid init() {memset(head, -1, sizeof(head));memset(maxson, -1, sizeof(maxson));ecnt = idcnt = 0;}void adde(int uu, int vv, int ww, int id) {u[ecnt] = uu; v[ecnt] = vv; w[ecnt] = ww; eid[ecnt] = id;nxt[ecnt] = head[uu]; head[uu] = ecnt++;}void dfs1(int now, int nowfa, int nowdep) {fa[now] = nowfa; dep[now] = nowdep;siz[now] = 1;for(int i = head[now]; ~i; i = nxt[i]) if(v[i] != nowfa) {dfs1(v[i], now, nowdep + 1);siz[now] += siz[v[i]];if(maxson[now] == -1 || siz[v[i]] > siz[maxson[now]]) {maxson[now] = v[i];}}}void dfs2(int now, int tp) {top[now] = tp;tid[now] = ++idcnt;if(maxson[now] == -1) return;dfs2(maxson[now], tp);for(int i = head[now]; ~i; i = nxt[i]) {if(v[i] != fa[now] && v[i] != maxson[now]) {dfs2(v[i], v[i]);}}}void pushup(int rt) {minv[rt] = min(minv[rt << 1], minv[rt << 1 | 1]);maxv[rt] = max(maxv[rt << 1], maxv[rt << 1 | 1]);}void pushdown(int rt) {if(lazy[rt] == 0) return;int lc = rt << 1, rc = rt << 1 | 1;lazy[lc] ^= lazy[rt]; lazy[rc] ^= lazy[rt];swap(minv[lc], maxv[lc]); swap(minv[rc], maxv[rc]);minv[lc] = -minv[lc]; minv[rc] = -minv[rc];maxv[lc] = -maxv[lc]; maxv[rc] = -maxv[rc];lazy[rt] = 0;}void build(int rt, int l, int r) {int mid = (l + r) >> 1;lazy[rt] = 0;if(l == r) {minv[rt] = maxv[rt] = sval[l];}else {build(lson); build(rson);pushup(rt);}}void change(int rt, int l, int r, int pos, int val) {if(l == r) {minv[rt] = maxv[rt] = val;}else {int mid = (l + r) >> 1;pushdown(rt);if(pos <= mid) change(lson, pos, val);else change(rson, pos, val);pushup(rt);}}void update(int rt, int l, int r, int ql, int qr) {if(ql <= l && qr >= r) {swap(minv[rt], maxv[rt]);minv[rt] = -minv[rt]; maxv[rt] = -maxv[rt];lazy[rt] ^= 1;}else {int mid = (l + r) >> 1;pushdown(rt);if(ql <= mid) update(lson, ql, qr);if(qr > mid) update(rson, ql, qr);pushup(rt);}}int query(int rt, int l, int r, int ql, int qr) {if(ql <= l && qr >= r) return maxv[rt];int mid = (l + r) >> 1, ret = -1e9;pushdown(rt);if(ql <= mid) ret = max(ret, query(lson, ql, qr));if(qr > mid) ret = max(ret, query(rson, ql, qr));pushup(rt);return ret;}int ask(int x, int y) {int ret = -1e9;while(top[x] != top[y]) {if(dep[top[x]] < dep[top[y]])swap(x, y);ret = max(ret, query(1, 1, idcnt, tid[top[x]], tid[x]));x = fa[top[x]];}if(dep[x] > dep[y]) swap(x, y);if(x != y) ret = max(ret, query(1, 1, idcnt, tid[x] + 1, tid[y]));return ret;}void Negate(int x, int y) {while(top[x] != top[y]) {if(dep[top[x]] < dep[top[y]]) swap(x, y);update(1, 1, idcnt, tid[top[x]], tid[x]);x = fa[top[x]];}if(dep[x] > dep[y]) swap(x, y);if(x != y) update(1, 1, idcnt, tid[x] + 1, tid[y]);}void debug() {for(int i = 1; i <= n; i++) {printf("for %d top is %d tid is %d val is %d\n", i, top[i], tid[i], sval[tid[i]]);}printf("the maxv: ");for(int i = 1; i <= n << 2; i++) printf("%d ", maxv[i]);puts("");}int main() {int T; scanf("%d", &T);while(T--) {init();scanf("%d", &n);for(int i = 1; i < n; i++) {int a, b, c;scanf("%d%d%d", &a, &b, &c);adde(a, b, c, i); adde(b, a, c, i);}dfs1(1, 1, 1); dfs2(1, 1);for(int i = 0; i < ecnt; i++) {if(dep[u[i]] > dep[v[i]]) {sval[tid[u[i]]] = w[i];rnum[eid[i]] = tid[u[i]];}else {sval[tid[v[i]]] = w[i];rnum[eid[i]] = tid[v[i]];}}build(1, 1, idcnt);//debug();char cmd[16];int x, y;while(scanf("%s", cmd)) {if(strcmp(cmd, "DONE") == 0) break;scanf("%d%d", &x, &y);if(cmd[0] == ‘Q‘) {printf("%d\n", ask(x, y));}else if(cmd[0] == ‘C‘) {change(1, 1, idcnt, rnum[x], y);}else {Negate(x, y);}}}return 0;}

　　

Poj 3237 TREE tree chain partitioning