树状数组

1. POJ 3468 :树状数组的解法代码比线段树要短

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
#include<utility>
#include<vector>
#include<cstring>
#include<cmath>
#define INF 0x3fffffff
#define pb push_back
#define pn(x) cerr<<x<<endl

using namespace std;
typedef long long ll;
const int maxv=100005;

typedef pair<int,ll> node;
int N,Q;
int a[maxv];
struct BIT{
    ll bit[maxv*2];
    void add(int i,int a){
        while(i<maxv*2){
            bit[i]+=a;
            i+=i&(-i);
        }
    }
    ll sum(int i){
        
        ll ans=0;
        while(i>0){
            ans+=bit[i];
            i-=i&-i;
        }
        return ans;
    }
};
//////查询所得的区间和为A[i]+B[i]*i
BIT A,B;
int main(){
    freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    cin>>N>>Q;
    for(int i=1;i<=N;i++){
        scanf("%d",&a[i]);
        A.add(i,a[i]);
    }
    while(Q--){
        char q;
        cin>>q;
        if(q=='Q'){
            int a,b;
            scanf("%d%d",&a,&b);
            printf("%I64d\n",A.sum(b)+b*B.sum(b)-(A.sum(a-1)+(a-1)*B.sum(a-1)));
        }
        else{
            int a,b,c;
            scanf("%d%d%d",&a,&b,&c);
            B.add(a,c);
            B.add(b+1,-c);
            A.add(b+1,c*b);
            A.add(a,-c*(a-1));
        }
    }
    return 0;
}