HDU 1166 - 敌兵布阵 - Segment Tree

题目传送门：HDU 1166 - 敌兵布阵

单点更新，区间求和

线段树入门题  也是树状数组的入门题

线段树AC Code：

//AcerGY
//#pragma comment (linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
#include <vector>
#include <cmath>
#define ll long long
#define BUG puts("BUG!")
#define ci(val) scanf("%d",&val)
#define pi(val) printf("%d\n",val)
#define clr(a,val) memset(a,val,sizeof(a))
#define lowbit(x) ((x)&(-x))
#define inf 0x3f3f3f3f
#define inf64 1LL<<60
#define PI acos(-1.0)
#define eps 1e-8

//Game Theory
#define P "First"
#define N "Second"

#define maxn 50010
#define mod 10009

using namespace std;

void readfile(char s[])
{
#ifndef ONLINE_JUDGE
	freopen(s,"r",stdin);
#endif
}

#define lson l,mid,root<<1
#define rson mid+1,r,root<<1|1

int seg[maxn<<2];

void push(int root)
{
	seg[root] = seg[root<<1]+seg[root<<1|1];
}
void build(int l,int r,int root)
{
	if(l==r)
	{
		scanf("%d",&seg[root]);
		return;
	}
	int mid = (l+r)>>1;
	build(lson);build(rson);
	push(root);
}
void update(int pos,int val,int l,int r,int root)
{
	if(l==r)
	{
		seg[root] += val;
		return;
	}
	int mid = (l+r)>>1;
	if(pos<=mid)
		update(pos,val,lson);
	else
		update(pos,val,rson);
	push(root);
}
int query(int L,int R,int l,int r,int root)
{
	int sum = 0;
	if(L<=l && r<=R)
		return seg[root];
	int mid = (l+r)>>1;
	if(L<=mid)
		sum += query(L,R,lson);
	if(R>mid)
		sum += query(L,R,rson);
	return sum;
}
int main()
{
	ios::sync_with_stdio(0);
	readfile("1166.txt");
	int T , cas = 1 , pos ,val;
	scanf("%d",&T);
	while(T--)
	{
		printf("Case %d:\n",cas++);
		int n;scanf("%d",&n);
		build(1,n,1);
		char op[10];
		while(~scanf("%s",op))
		{
			if(op[0]=='E')
				break;
			scanf("%d%d",&pos,&val);
			if(op[0]=='A')
				update(pos,val,1,n,1);
			else if(op[0]=='S')
				update(pos,-val,1,n,1);
			else
				printf("%d\n",query(pos,val,1,n,1));
		}
	}
	return 0;
}

树状数组AC Code：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
using namespace std;

const int maxn = 50010;

int n,a[maxn],tree[maxn];

int lowbit(int x)
{
    return x&(-x);
}
void update(int i,int val)
{
    while(i<=n)
    {
        tree[i] += val;
        i += lowbit(i);
    }
}
int query(int i)
{
    int sum = 0;
    while(i>0)
    {
        sum += tree[i];
        i -= lowbit(i);
    }
    return sum;
}

int main()
{
    int t , cas = 1;
    scanf("%d",&t);
    string op;
    int u , v;
    while(t--)
    {
        memset(tree,0,sizeof(tree));
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
            update(i,a[i]);
        }
        printf("Case %d:\n",cas++);
        while(cin>>op && op[0]!='E')
        {
            if(op[0]=='A')
            {
                scanf("%d%d",&u,&v);
                update(u,v);
            }
            else if(op[0]=='S')
            {
                scanf("%d%d",&u,&v);
                update(u,-v);
            }
            else if(op[0]=='Q')
            {
                scanf("%d%d",&u,&v);
                printf("%d\n",query(v)-query(u-1));
            }
        }
    }
    return 0;
}