HDU-1166-敌兵布阵(线段树)(树状数组)

• 线段树（kuangbin本题链接）

  #include "bits/stdc++.h"
  using namespace std;
  const int MAXN = 50010;
  struct Node {
      int l, r;
      int sum;
  } segTree[MAXN * 4];
  void build(int i, int l, int r) {
      segTree[i].l = l;
      segTree[i].r = r;
      if (l == r) {
          scanf("%d", &segTree[i].sum);
          return;
      }
      int mid = l + r >> 1;
      build(i << 1, l, mid);
      build(i << 1 | 1, mid + 1, r);
      segTree[i].sum = segTree[i << 1].sum + segTree[i << 1 | 1].sum;
  }
  void add(int i, int k, int v) {
      segTree[i].sum += v;
      if (segTree[i].l == segTree[i].r) return;
      int mid = segTree[i].l + segTree[i].r >> 1;
      if (k <= mid) add(i << 1, k, v);
      else add(i << 1 | 1, k, v);
  }
  int query(int i, int l, int r) {
      if (segTree[i].l == l && segTree[i].r == r) return segTree[i].sum;
      int mid = segTree[i].l + segTree[i].r >> 1;
      if (r <= mid) return query(i << 1, l, r);
      else if (l > mid) return query(i << 1 | 1, l, r);
      else return query(i << 1, l, mid) + query(i << 1 | 1, mid + 1, r);
  }
  int main() {
      int t, n; char op[10];
      scanf("%d", &t);
      for (int ca = 1; ca <= t; ca++) {
          printf("Case %d:\n", ca);
          scanf("%d", &n);
          build(1, 1, n);
          int x, y;
          while (scanf("%s", op) && op[0] != 'E') {
              scanf("%d%d", &x, &y);
              if (op[0] == 'Q') printf("%d\n", query(1, x, y));
              else if (op[0] == 'A') add(1, x, y);
              else add(1, x, -y);
          }
      }
      return 0;
  }

  修改自2019年6月6日，删除了原先的线段树代码，原先不喜欢用结构体定义线段树的节点，现在感觉到用结构体代码清晰一点。模仿的kuangbin模板。

• 树状数组

  #include"cstdio"
  #include"cstring"
  using namespace std;
  int tree[50005],N,x,y;
  //用来求x二进制码从右往左数第一个1所在位的值
  int lowbit(int x){
      return x&-x;
  }
  void Add(int x){
      while(x<=N){
          tree[x]+=y;
          x+=lowbit(x);
      }
  }
  int Query(int x){
      int ans=0;
      while(x){
          ans+=tree[x];
          x-=lowbit(x);
      }
      return ans;
  }
  int main(){
      int T;char s[10];
      scanf("%d",&T);
      for(int k=1;k<=T;k++){
          memset(tree,0,sizeof(tree));
          scanf("%d",&N);
          for(int i=1;i<=N;i++){
              scanf("%d",&y);
              Add(i);
          }
          printf("Case %d:\n",k);
          while(scanf("%s",s)&&s[0]!='E'){
              scanf("%d%d",&x,&y);
              if(s[0]=='Q')printf("%d\n",Query(y)-Query(x-1));
              else {
                  if(s[0]=='S')y=-y;
                  Add(x);
              }
          }
      }
      return 0;
  }