线段树模板

hdu1166 单点更新+区间查询
[http://acm.hdu.edu.cn/showproblem.php?pid=1166]

#include <iostream>
#include <stdio.h>
#include <string.h>
#define lson l, mid, rt<<1
#define rson mid + 1, r, rt<<1|1
using namespace std;
const int MAXN = 50010;
int tree[MAXN<<2];  //tree[rt]存储rt对应区间的最大值

void push_up(int rt){   //更新rt的值
    tree[rt] = tree[rt<<1]+tree[rt<<1|1];
}

//建树
void build(int l, int r, int rt){//rt对应区间[l, r]
    if(l == r){
        scanf("%d", &tree[rt]); //叶子节点总共为n个
        return;
    }
    int mid = (l+r)>>1;
    build(lson);    //更新左子树
    build(rson);    //更新右子树
    push_up(rt);    //向上更新
}

//单点修改
void updata(int p, int sc, int l, int r, int rt){
    if(l == r){             //找到p点
        tree[rt] += sc;     //从叶子节点开始修改
        return;
    }
    int mid = (l + r) >> 1;
    if(p <= mid) updata(p, sc, lson);
    else updata(p, sc, rson);
    push_up(rt);            //向上更新节点
}

//求区间[L, R]的区间和，初始值l，r别为1，n，rt=1
int query(int L, int R, int l, int r, int rt){
    if(L <= l && R >= r) return tree[rt];   //如果[l,r]在区间[L,R]中则直接返回该区间和
    int cnt = 0;
    int mid = (l + r) >> 1;
    if(L <= mid) cnt += query(L, R, lson);  //L在mid左边
    if(R > mid) cnt += query(L, R, rson);   //R在mid右边
    return cnt;
}

int main(){
    int n, m;
    scanf("%d", &m);
    int ans = 1;
    while(m--){
        printf("Case %d:\n", ans++);
        memset(tree, 0, sizeof(0));
        scanf("%d", &n);
        build(1, n, 1);
        while(1){
            char str[10];
            scanf("%s", str);
            if(str[0]!='E'){
                int x, y;
                scanf("%d%d", &x, &y);
                if(str[0] == 'A'){
                    updata(x, y, 1, n, 1);
                }else if(str[0] == 'S'){
                    updata(x, -y, 1, n, 1);
                }else if(str[0] == 'Q'){
                    printf("%d\n", query(x, y, 1, n, 1));
                }
            }else break;
        }
    }
    return 0;
}

hud1754
求区间最大值，单点更改

#include <iostream>
#include <stdio.h>
#include <string.h>
#define lson l, mid, rt<<1
#define rson mid + 1, r, rt<<1|1
using namespace std;
const int MAXN = 2e5 + 10;
int tree[MAXN<<2];//tree[rt]存储rt对应区间的最大值

void push_up(int rt){//更新rt的值
    tree[rt] = max(tree[rt<<1], tree[rt<<1|1]);
}

//建树
void build(int l, int r, int rt){//rt对应区间[l, r]
    if(l == r){
        scanf("%d", &tree[rt]);
        return;
    }
    int mid = (l+r)>>1;
    build(lson);
    build(rson);
    push_up(rt);//向上更新
}

//单点替换
void updata(int p, int sc, int l, int r, int rt){//将p点值替换成sc
    if(l == r){//找到p点
        tree[rt] = sc;
        return;
    }
    int mid = (l + r) >> 1;
    if(p <= mid) updata(p, sc, lson);
    else updata(p, sc, rson);
    push_up(rt);//向上更新节点
}

//求区间最值
int query(int L, int R, int l, int r, int rt){//查询[L, R]内最大值
    if(L <= l && R >= r) return tree[rt];//当前区间[l, r]包含在[L, R]中
    int cnt = 0;
    int mid = (l + r) >> 1;
    if(L <= mid) cnt = max(cnt, query(L, R, lson));//L在mid左边
    if(R > mid) cnt = max(cnt, query(L, R, rson));//R在mid右边
    return cnt;
}

int main(){
    int n, m;
    while(~scanf("%d%d", &n, &m)){
        build(1, n, 1);
        char str[10];
        int x, y;
        while(m--){
            scanf("%s%d%d", str, &x, &y);
            if(str[0] == 'U') updata(x, y, 1, n, 1);
            else printf("%d\n", query(x, y, 1, n, 1));
        }
    }
    return 0;
}