A Simple Problem with Integers POJ - 3468 (线段树)

思路：线段树，区间更新，区间查找

 #include<iostream>
 #include<vector>
 #include<string>
 #include<cmath>
 #include<set>
 #include<algorithm>
 #include<cstdio>
 #include<map>
 #include<cstring>
 #include<list>

 #define MAXSIZE 100010

 using namespace std;

 long long tree[*MAXSIZE];
 long long lz[*MAXSIZE];
 int N, Q;

 void init()
 {
     memset(tree, , sizeof(tree));
     memset(lz, , sizeof(lz));
 }

 void build(int node, int l, int r)
 {
     if(l == r)
     {
         scanf("%lld", &tree[node]);
         return;
     }

     int mid = (l+r)/;
     build(node*, l, mid);
     build(node*+, mid+, r);

     tree[node] = tree[node*] + tree[node*+];
 }

 void push_down(int node, int l, int r)
 {
     if(lz[node])
     {
         int mid = (l+r)/;
         lz[node*] += lz[node];
         lz[node*+] += lz[node];
         tree[node*] += (mid-l+)*lz[node];
         tree[node*+] += (r-mid)*lz[node];
         lz[node] = ;
     }
 }

 void update_range(int node, int l, int r, int L, int R, int add)
 {
     if(l <= L && r >= R)
     {
         lz[node] += add;
         tree[node] += (R-L+)*add;
         return;
     }
     push_down(node, L, R);
     int mid = (L+R)/;
     if(mid >= l)
         update_range(node*, l, r, L, mid, add);
     if(mid < r)
         update_range(node*+, l, r, mid+, R, add);
     tree[node] = tree[node*] + tree[node*+];
 }

 long long query_range(int node, int l, int r, int L, int R)
 {
     if(l <= L && r >= R)
     {
         return tree[node];
     }
     push_down(node, L, R);
     int mid = (L+R)/;
     long long sum = ;
     if(mid >= l)
         sum += query_range(node*, l, r, L, mid);
     if(mid < r)
         sum += query_range(node*+, l, r, mid+, R);

     return sum;
 }

 int main()
 {
     scanf("%d%d", &N, &Q);
     init();
     build(, , N);
     while(Q--)
     {
         char ch;
         scanf(" %c", &ch);
         if(ch == 'Q')
         {
             int a, b;
             scanf("%d%d", &a, &b);
             printf("%lld\n", query_range(, a, b, , N));
         }
         else if(ch == 'C')
         {
             int a, b, c;
             scanf("%d%d%d", &a, &b, &c);
             update_range(, a, b, , N, c);
         }
     }

     return ;
 }