hdu 1166 敌兵布阵 【线段树】

好好学一下线段树----

从0开始----加油～

单点更新的

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<vector>
using namespace std;
#define lp (p << 1)
#define rp (p << 1 | 1)
#define getmid(l,r) (l + (r - l) / 2)

const int maxn = 50005;
struct node{
    int l,r,s;
}t[4*maxn];

int a[maxn],n;

int calc(int a,int b) { return a+b; }

void Push_up(int p){
    t[p].s = calc(t[lp].s,t[rp].s);
}

void Build_tree(int p,int l,int r){
    t[p].l = l;
    t[p].r = r;
    if(l == r){ t[p].s = a[l];return;}
    int mid = getmid(l,r);
    Build_tree(lp,l,mid);
    Build_tree(rp,mid+1,r);
    Push_up(p);
}

void update(int p,int s,int w){//给s点加上w 
    if(t[p].l == t[p].r) {
        t[p].s += w;
        return;
    }
    int mid = getmid(t[p].l,t[p].r);
    if(s <= mid) update(lp,s,w);
    else update(rp,s,w);
    Push_up(p);        
}

int sum(int p,int l,int r){
    if(t[p].l == l && t[p].r == r) return t[p].s;
    
        int mid = getmid(t[p].l,t[p].r);
        if(r <= mid) return sum(lp,l,r);
        else if(mid < l) return sum(rp,l,r);
         else return calc(sum(lp,l,mid),sum(rp,mid+1,r));
}

int main(){
    int T;
    scanf("%d",&T);
    int kase = 0;
    while(T--){
        scanf("%d",&n);
        for(int i = 1;i <= n;i++) scanf("%d",&a[i]);
        Build_tree(1,1,n);
        
    //    for(int i = 1;i <= n;i++)
    //    printf("t[%d].l = %d  t[%d].r = %d  t[%d].s = %d
",i,t[i].l,i,t[i].r,i,t[i].s);
        
        char cmd[10];
        int x,y;
        printf("Case %d:
",++kase);
        while(cin >> cmd){
            if(cmd[0] == 'E') break;
            else if(cmd[0] == 'A'){
            scanf("%d %d",&x,&y);
            update(1,x,y);
            }
            else if(cmd[0] == 'S'){
            scanf("%d %d",&x,&y);
            update(1,x,-y);
            }
            else{
                scanf("%d %d",&x,&y);
                printf("%d
",sum(1,x,y));
            }
        }    
    }
    return 0;
}