蓝桥杯 算法训练 操作格子 [ 线段树 ]

  1 #include <iostream>
  2 #include <cstdlib>
  3 #include <cstdio>
  4 #include <algorithm>
  5 #include <cstring>
  6 #include <vector>
  7 #include <queue>
  8 using namespace std;
  9 
 10 #define ll long long
 11 
 12 const int N = 100005;
 13 const ll inf = 0x3f3f3f3f;
 14 
 15 int n,m;
 16 int a[N];
 17 int sum[N*4],ma[N*4];
 18 
 19 void build(int i,int l,int r)
 20 {
 21     if(l==r){
 22         sum[i]=ma[i]=a[l];
 23         return;
 24     }
 25     int mid=(l+r)/2;
 26     build(i*2,l,mid);
 27     build(i*2+1,mid+1,r);
 28     ma[i]=max(ma[i*2],ma[i*2+1]);
 29     sum[i]=sum[i*2]+sum[i*2+1];
 30     return;
 31 }
 32 
 33 void setValue(int i,int l,int r,int x,int y)
 34 {
 35     if(l==r){
 36         ma[i]=sum[i]=a[x]=y;
 37         return;
 38     }
 39     int mid=(l+r)/2;
 40     if(x<=mid)
 41         setValue(i*2,l,mid,x,y);
 42     else
 43         setValue(i*2+1,mid+1,r,x,y);
 44     ma[i]=max(ma[i*2],ma[i*2+1]);
 45     sum[i]=sum[i*2]+sum[i*2+1];
 46 }
 47 
 48 int querysum(int i,int l,int r,int x,int y)
 49 {
 50     if(x>r || y<l){
 51         return 0;
 52     }
 53     else if(x<=l && r<=y){
 54         return sum[i];
 55     }
 56     int mid=(l+r)/2;
 57     int lsum=0,rsum=0;
 58     if(mid>=x){
 59         lsum=querysum(i*2,l,mid,x,y);
 60     }
 61     if(mid<y){
 62         rsum=querysum(i*2+1,mid+1,r,x,y);
 63     }
 64     return lsum+rsum;
 65 }
 66 
 67 int queryma(int i,int l,int r,int x,int y)
 68 {
 69     if(x>r || y<l){
 70         return 0;
 71     }
 72     else if(x<=l && r<=y){
 73         return ma[i];
 74     }
 75     int mid=(l+r)/2;
 76     int lma=0,rma=0;
 77     if(mid>=x){
 78         lma=queryma(i*2,l,mid,x,y);
 79     }
 80     if(mid<y){
 81         rma=queryma(i*2+1,mid+1,r,x,y);
 82     }
 83     return max(lma,rma);
 84 }
 85 
 86 int main()
 87 {
 88     int i;
 89     int p,x,y;
 90     //freopen("data.in","r",stdin);
 91     scanf("%d%d",&n,&m);
 92     for(i=1;i<=n;i++){
 93         scanf("%d",&a[i]);        
 94     }
 95     build(1,1,n);
 96     for(i=1;i<=m;i++){
 97         scanf("%d%d%d",&p,&x,&y);
 98         if(p==1){
 99             setValue(1,1,n,x,y);
100         }
101         else if(p==2){
102             printf("%d\n",querysum(1,1,n,x,y));
103         }
104         else{
105             printf("%d\n",queryma(1,1,n,x,y));
106         }
107     }
108     
109     return 0;
110 }