POJ2892 Tunnel Warfare (line segment tree)

Click the open question link to perform three operations and inquiries on consecutive villages.

1. D x:X-Th village was destroyed.
2. Q x: The Army commands requested the number of commands ages thatX-Th village was directly or indirectly connected with including itself.
3. R: The village destroyed last was rebuilt.

Update the continuous interval. If the node status in the current interrogation interval is the same, the continuous value of the current interval is returned. Otherwise, recursive queries are performed based on the relationship between the current query vertex number and the left and right intervals.

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.StreamTokenizer;public class Main{class SegTree {class node {int left, right;int sum, lsum, rsum;int mid() {return (left + right) >>1;}int dis() {return (right - left + 1);}void init(int t) {sum = lsum = rsum = t *dis();}}node tree[];SegTree(int maxn) {tree = new node[maxn * 5];}void init(int left, int right, int idx) {tree[idx] = new node();tree[idx].left=left;tree[idx].right=right;tree[idx].init(1);if (left == right)return;int mid = tree[idx].mid();init(left, mid, idx << 1);init(mid + 1, right, (idx << 1)|1);}void update(int id, int v, int idx) {if (tree[idx].left == tree[idx].right) {tree[idx].init(v);return;}int mid = tree[idx].mid();if (id <= mid)update(id, v, idx << 1);elseupdate(id, v, (idx << 1) + 1);        pushup(idx);}int query(int id, int idx) {if (tree[idx].sum == 0|| tree[idx].sum == tree[idx].dis())return tree[idx].sum;int mid = tree[idx].mid();if (id <= mid) {if (id > mid - tree[idx << 1].rsum)return query(id, idx << 1) + query(mid + 1, (idx << 1) + 1);elsereturn query(id, idx << 1);} else {if (id < mid + 1 + tree[(idx << 1)|1].lsum)return query(id, (idx << 1)|1) + query(mid, idx << 1);elsereturn query(id, (idx << 1)|1);}}void pushup(int idx){int l = idx << 1;int r = (idx << 1)|1;tree[idx].sum = Math.max(tree[l].rsum + tree[r].lsum,Math.max(tree[r].sum, tree[l].sum));tree[idx].lsum = tree[l].lsum;tree[idx].rsum = tree[r].rsum;if (tree[l].sum == tree[l].dis())tree[idx].lsum += tree[r].lsum;if (tree[r].sum == tree[r].dis())tree[idx].rsum += tree[l].rsum;}} StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));final int next() throws IOException {in.nextToken();return (int) in.nval;}void run() throws IOException {int n=next();int m=next();SegTree st=new SegTree(n);st.init(1,n, 1);int stack[]=new int[m];boolean des[]=new boolean[n+1];int top=0,k;while(m-->0){in.nextToken();String s=in.sval;if(s.charAt(0)=='D'){k=next();stack[++top]=k;des[k]=true;st.update(k,0,1);}if(s.charAt(0)=='Q'){k=next();if(des[k])System.out.println(0);elseSystem.out.println(st.query(k,1));}if(s.charAt(0)=='R'){k=stack[top--];des[k]=false;st.update(k, 1, 1);}}}public static void main(String[] args) throws IOException {          new Main().run();}}