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推荐黄嘉泰的线段树合并
HNOI永无乡
#include <stdio.h>
#define maxn 100010
int n, m, id[maxn];
struct Edge{int to, nxt;}edge[maxn << 1];
int h[maxn], cnt;
void add(int u, int v){
edge[++ cnt] = (Edge){v, h[u]}; h[u] = cnt;
edge[++ cnt] = (Edge){u, h[v]}; h[v] = cnt;
}
int root[maxn], val[maxn];
bool vis[maxn];
int fa[maxn];
int getfa(int x){return x == fa[x] ? x : fa[x] = getfa(fa[x]);}
#define TREE 5000010
int lc[TREE], rc[TREE], size[TREE], Size;
void insert(int& rt, int l, int r, int x){
if(!rt)rt = ++ Size;
size[rt] ++;
if(l == r)return;
int mid = l + r >> 1;
if(x <= mid)insert(lc[rt], l, mid, x);
else insert(rc[rt], mid+1, r, x);
}
int merge(int x, int y){
if(x == 0 || y == 0)return x + y;
lc[x] = merge(lc[x], lc[y]);
rc[x] = merge(rc[x], rc[y]);
size[x] = size[lc[x]] + size[rc[x]];
return x;
}
int ask(int rt, int l, int r, int k){
if(l == r)return id[l];
int mid = l + r >> 1;
if(k <= size[lc[rt]])
return ask(lc[rt], l, mid, k);
k -= size[lc[rt]];
return ask(rc[rt], mid+1, r, k);
}
int main(){
scanf("%d%d", &n, &m);
static int w[maxn];
for(int i = 1; i <= n; i ++)
scanf("%d", &val[i]), id[val[i]] = i;
int u, v;
for(int i = 1; i <= n; i ++)fa[i] = i;
for(int i = 1; i <= m; i ++){
scanf("%d%d", &u, &v);
u = getfa(u), v = getfa(v);
fa[getfa(v)] = getfa(u);
}
for(int i = 1; i <= n; i ++)
insert(root[getfa(i)], 1, n, val[i]);
int test; char cmd[2];
scanf("%d", &test);
while(test --){
scanf("%s", cmd);
if(cmd[0] == ‘Q‘){
scanf("%d%d", &u, &v), u = getfa(u);
if(size[root[u]] < v){puts("-1");continue;}
printf("%d\n", ask(root[u], 1, n, v));
}
else{
scanf("%d%d", &u, &v);
u = getfa(u), v = getfa(v);
if(u == v)continue;
root[u] = merge(root[u], root[v]);
fa[getfa(v)] = getfa(u);
}
}
return 0;
}
[BZOJ 3702]二叉树
#include <bits/stdc++.h>
#define maxn 400010
#define TREE 5000010
using namespace std;
int n, son[maxn][2], w[maxn], root[maxn];
int cnt;
int get_tree(){
int x = ++ cnt, a;
scanf("%d", &a);
if(a)w[x] = a;
else{
son[x][0] = get_tree();
son[x][1] = get_tree();
}
return x;
}
typedef long long ll;
ll sum1, sum2, ans, sz[TREE];
int lc[TREE], rc[TREE], tr_cnt;
int merge(int x, int y){
if(x == 0 || y == 0)return x + y;
sum1 += sz[lc[x]] * sz[rc[y]];
sum2 += sz[lc[y]] * sz[rc[x]];
lc[x] = merge(lc[x], lc[y]);
rc[x] = merge(rc[x], rc[y]);
sz[x] = sz[lc[x]] + sz[rc[x]];
return x;
}
void insert(int &rt, int l, int r, int x){
rt = ++ tr_cnt;
sz[rt] = 1;
if(l == r)return;
int mid = l + r >> 1;
if(x <= mid) insert(lc[rt], l, mid, x);
else insert(rc[rt], mid+1, r, x);
}
void dfs(int x){
if(son[x][0] && son[x][1]){
dfs(son[x][0]); dfs(son[x][1]);
sum1 = sum2 = 0;
root[x] = merge(root[son[x][0]], root[son[x][1]]);
ans += min(sum1, sum2);
}
else insert(root[x], 1, n, w[x]);
}
int main(){
scanf("%d", &n);
int root = get_tree();
dfs(root);
printf("%lld\n", ans);
return 0;
}
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原文地址:http://www.cnblogs.com/Candyouth/p/5487069.html