[模板]树状数组

1.单点修改区间查询

OJ题号：洛谷P3374

#include<cstdio>
#include<cstring>
#define maxn 500000
int n,m;
struct BIT {
    int val[maxn];
    BIT() {
        memset(val,0,sizeof val);
    }
    int lowbit(int x) {
        return x&-x;
    }
    void modify(int p,const int x) {
        while(p<=n) {
            val[p]+=x;
            p+=lowbit(p);
        }
    }
    int query(int p) {
        int ans=0;
        while(p) {
            ans+=val[p];
            p-=lowbit(p);
        }
        return ans;
    }
};
BIT tree;
int main() {
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++) {
        int x;
        scanf("%d",&x);
        tree.modify(i,x);
    }
    while(m--) {
        int op,x,y;
        scanf("%d%d%d",&op,&x,&y);
        if(op==1) {
            tree.modify(x,y);
        }
        else {
            printf("%d
",tree.query(y)-tree.query(x-1));
        }
    }
    return 0;
}

 2.区间修改单点查询

OJ题号：洛谷P3368

#include<cstdio>
#include<cstring>
#define maxn 500001
int n,m,a[maxn];
struct BIT {
    int val[maxn];
    BIT() {
        memset(val,0,sizeof val);
    }
    int lowbit(const int x) {
        return x&-x;
    }
    void modify(int p,const int x) {
        while(p) {
            val[p]+=x;
            p-=lowbit(p);
        }
    }
    int query(int p) {
        int ans=0;
        while(p<=n) {
            ans+=val[p];
            p+=lowbit(p);
        }
        return ans;
    }
};
BIT tree;
int main() {
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++) {
        scanf("%d",&a[i]);
    }
    while(m--) {
        int op;
        scanf("%d",&op);
        if(op==1) {
            int x,y,k;
            scanf("%d%d%d",&x,&y,&k);
            tree.modify(y,k);
            tree.modify(x-1,-k);
        }
        else {
            int x;
            scanf("%d",&x);
            printf("%d
",a[x]+tree.query(x));
        }
    }
    return 0;
}