LOJ P10116 清点人数 题解

每日一题 day13 打卡

Analysis

用简单的树状数组维护单点修改和查询就行了

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #define maxn 500000+10
 using namespace std;
 inline int read()
 {
     int x=;
     bool f=;
     char c=getchar();
     for(; !isdigit(c); c=getchar()) if(c=='-') f=;
     for(; isdigit(c); c=getchar()) x=(x<<)+(x<<)+c-'';
     if(f) return x;
     return -x;
 }
 inline void write(int x)
 {
     if(x<){putchar('-');x=-x;}
     if(x>) write(x/);
     putchar(x%+'');
 }
 int n,k;
 int tree[maxn];
 inline int lowbit(int num){return num&-num;}
 inline void build(int s,int num)
 {
     for(int i=s;i<=n;i+=lowbit(i)) tree[i]+=num;
 }
 inline int ask(int s)
 {
     int ans=;
     for(int i=s;i>=;i-=lowbit(i)) ans+=tree[i];
     return ans;
 }
 int main()
 {
     n=read();k=read();
     for(int i=;i<=k;i++)
     {
         char in;
         scanf("%s",&in);
         if(in=='A')
         {
             int x=read();
             int res=ask(x);
             write(res);
             printf("\n");
         }
         if(in=='B')
         {
             int x=read(),y=read();
             build(x,y);
         }
         if(in=='C')
         {
             int x=read(),y=read();
             build(x,-y);
         }
     }
     return ;
 }

请各位大佬斧正（反正我不认识斧正是什么意思）