题目
题目链接:https://www.luogu.com.cn/problem/P3368
思路
求区间上的加减就要用差分数组!
代码
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<cctype>
#include<ctime>
#include<iostream>
#include<string>
#include<map>
#include<queue>
#include<stack>
#include<set>
#include<vector>
#include<iomanip>
#include<list>
#include<bitset>
#include<sstream>
#include<fstream>
#include<complex>
#include<algorithm>
#if __cplusplus >= 201103L
#include <unordered_map>
#include <unordered_set>
#endif
#define ll long long
using namespace std;
const int INF = 0x3f3f3f3f;
inline int lowbit(int x){
return (-x)&x;
}
int bit[500010];
int n,m;
void edit(int pos,int val){
for(int i=pos;i<=n;i+=lowbit(i)){
bit[i]+=val;
}
}
int query(int pos){
int res=0;
for(int i=pos;i>=1;i-=lowbit(i)){
res+=bit[i];
}
return res;
}
int main(){
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//int n,m;
cin>>n>>m;
for(int i=1;i<=n;i++){
int t;
cin>>t;
edit(i,t);
edit(i+1,-t);
}
int st;
// cout<<query(2)<<endl;
for(int i=1;i<=m;i++){
cin>>st;
if(st==1){
int a,b,c;
cin>>a>>b>>c;
edit(a,c);
edit(b+1,-c);
}
else {
int a;
cin>>a;
cout<<query(a)<<endl;
}
}
return 0;
}