Segment Tree hdu1166

Left son of line segment tree node [A, (A+B)/2] right son [(a+b)/2,b]

This is important.

The line tree as a complete binary tree calculation, open to 3*n, but it is best to 4*n

#include <bits/stdc++.h>using namespace std;int a[50005];struct {int sum; int left,right;}    b[50005*4];void Build (int left,int right,int i) {int mid;    B[i].left=left;b[i].right=right;        if (left==right) {b[i].sum=a[left];    return;    } mid = (left+right)/2;    Build (Left,mid,2*i);    Build (mid+1,right,2*i+1); B[i].sum=b[2*i].sum+b[2*i+1].sum;}    int Query (int left,int right,int i) {int mid;    if (b[i].left==left&&b[i].right==right) return b[i].sum;    Mid= (B[i].left + b[i].right)/2;    if (right <= mid) return Query (left,right,2*i);    else if (Left > Mid) return Query (left,right,2*i+1); else return query (left,mid,2*i) + query (mid+1,right,2*i+1);}    void Add (int id,int num,int i) {if (B[i].left = = b[i].right) {b[i].sum = b[i].sum + num; return;        } else {b[i].sum = b[i].sum + num;        if (id<=b[i*2].right) Add (id,num,2*i);    else Add (id,num,2*i+1);    }}int Main () {int t,kase=1;  scanf ("%d", &t);  while (t--) {memset (b,0,sizeof (b));        int n;        scanf ("%d", &n);        for (int i=1;i<=n;i++) scanf ("%d", &a[i]);        Build (1,n,1);        String S;int x, y;        printf ("Case%d:\n", kase++);            while (Cin>>s) {if (s[0]== ' E ') is break;            scanf ("%d%d", &x,&y);            if (s[0]== ' Q ') {printf ("%d\n", Query (x,y,1));            } if (s[0]== ' A ') {Add (x,y,1);        } if (s[0]== ' s ') Add (x,-y,1); }    }}

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Segment Tree hdu1166