HDU-1166 敌兵布阵

题目链接:https://vjudge.net/problem/HDU-1166

线段树模板题

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
#include<set>
#include<string>
#include<stack>
using namespace std;
typedef long long ll;
#define maxn 50000

struct node{
int l, r, sum;
int mid(){
return (l+r)/2;
}
};

node Tree[maxn*4];
int value[maxn+10];
int flag;

//初始化树，根节点是1
void init_tree(int root, int l, int r){
Tree[root].l = l;
Tree[root].r = r;
if(l == r)
Tree[root].sum = value[l];
else{
init_tree(2*root, l, (l+r)/2);
init_tree(2*root+1, (l+r)/2 + 1, r);

Tree[root].sum = Tree[2*root].sum + Tree[2*root+1].sum;
}
}

//查找和
int query_tree(int root, int l, int r){
int m = Tree[root].mid();
if(l == Tree[root].l && r == Tree[root].r)
return Tree[root].sum;
else{
if(l > m)
return query_tree(2*root+1, l, r);
else if(r <= m)
return query_tree(2*root, l, r);
else
return query_tree(2*root, l, m) + query_tree(2*root+1, m+1, r);
}
}

void update_tree(int root, int idx, int v){
if(Tree[root].l == Tree[root].r)
Tree[root].sum += flag*v;
else{
Tree[root].sum += flag*v;

if(idx <= Tree[root].mid())
update_tree(2*root, idx, v);
else
update_tree(2*root+1, idx, v);
}
}
int n;
int main()
{
//freopen("/home/zlwang/Desktop/t2.txt","r",stdin);
int T,kase=0;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
for(int i=0;i<n;i++)
scanf("%d",&value[i]);
init_tree(1,0,n-1);
printf("Case %d:\n",++kase);
char s[5];
int a,b;
while(~scanf("%s",s))
{
if(s[0]=='E') break;
scanf("%d%d",&a,&b);
if(s[0]=='Q')
{
printf("%d\n",query_tree(1,a-1,b-1));
}
else if(s[0]=='A')
{
flag=1;
update_tree(1,a-1,b);
}
else if(s[0]=='S')
{
flag=-1;
update_tree(1,a-1,b);
}
}
}
return 0;
}