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POJ 3468 A Simple Problem with Integers

线段树，涉及到了区间更新，代码在Update和Query中均涉及到了更新，使得程序在时间上有所优化。

  1 #include<cstdio>
  2 #define mid(a,b) ((a+b)>>1) //宏定义中用到移位需要注意！
  3 
  4 using namespace std;
  5 
  6 struct Node{
  7 
  8      int left, right;
  9      Node* pL, *pR;
 10      long long sum;
 11      long long increase;
 12 }Tree[400020];
 13 
 14 int Count = 0;
 15 
 16 void build(Node *pRoot, int l, int r){
 17 
 18    pRoot->left = l;
 19    pRoot->right = r;
 20    pRoot->sum = 0;
 21    pRoot->increase = 0;
 22 
 23    if( l == r )//结束条件
 24        return;
 25    Count ++;
 26    pRoot->pL = Tree + Count;
 27    Count ++;
 28    pRoot->pR = Tree + Count;
 29 
 30    build(pRoot->pL, l, mid(l,r));
 31    build(pRoot->pR, mid(l,r)+1, r);
 32 }
 33 
 34 void minsert(Node *pRoot, int pose, int value){
 35 
 36      if(pRoot->left == pose && pRoot->right == pose){
 37           pRoot->sum = value;
 38           return;
 39      }
 40      pRoot->sum += value;//important!
 41      if(pose <= mid(pRoot->left,pRoot->right))
 42         minsert(pRoot->pL, pose, value);
 43      else if(pose > mid(pRoot->left,pRoot->right))
 44         minsert(pRoot->pR,pose,value);
 45 }
 46 
 47 void add(Node *pRoot, int l, int r, long long value){
 48 
 49      if(pRoot->left == l && pRoot->right == r){
 50         pRoot->increase += value;
 51         return;
 52      }
 53 
 54      pRoot->sum += value*(r - l + 1);//右减左！此时增值为value！
 55      if(r <= mid(pRoot->left, pRoot->right))
 56         add(pRoot->pL, l, r, value);
 57      else if(l > mid(pRoot->left, pRoot->right))
 58         add(pRoot->pR, l, r, value);
 59      else{
 60         add(pRoot->pL, l, mid(pRoot->left, pRoot->right),value);
 61         add(pRoot->pR, mid(pRoot->left, pRoot->right) + 1, r, value);
 62      }
 63 }
 64 
 65 long long query(Node* pRoot, int s, int e){
 66 
 67     if(pRoot->left == s && pRoot->right == e){
 68         return pRoot->sum + pRoot->increase*(pRoot->right - pRoot->left + 1);
 69     }
 70 
 71     pRoot->sum += pRoot->increase*(pRoot->right - pRoot->left + 1);
 72     add(pRoot->pL, pRoot->left, mid(pRoot->left, pRoot->right), pRoot->increase);//
 73     add(pRoot->pR, mid(pRoot->left, pRoot->right) + 1, pRoot->right, pRoot->increase);//
 74     pRoot->increase = 0;
 75     if(e <= mid(pRoot->left, pRoot->right))
 76         return query(pRoot->pL, s, e);
 77     else if(s > mid(pRoot->left, pRoot->right))
 78         return query(pRoot->pR, s, e);//
 79     else{
 80         return query(pRoot->pL, s, mid(pRoot->left, pRoot->right)) +
 81                query(pRoot->pR, mid(pRoot->left, pRoot->right) + 1, e);
 82     }
 83 }
 84 
 85 int main(){
 86 
 87   int n, q, num, l, r, value;
 88   char op;
 89   scanf("%d %d", &n, &q);
 90 
 91   build(Tree, 1, n);
 92 
 93   for(int i = 1; i <= n; i++){
 94     scanf("%d", &num);
 95     minsert(Tree, i, num);
 96   }
 97   while(q --){
 98 
 99     getchar();
100     scanf("%c",&op);
101     if(op == 'C'){
102         scanf("%d %d %d", &l, &r, &value);
103         add(Tree, l, r, value);
104     }
105     if(op == 'Q'){
106         scanf("%d %d", &l, &r);
107         printf("%I64d
",query(Tree,l,r));
108     }
109   }
110 
111   return 0;
112 
113 }

View Code

实际上还是很渣的线段树，尽管有优化，但是，效率仍然很低。

140ms 和 1700+ms的区别。。。

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原文地址：https://www.cnblogs.com/pekary/p/3865835.html