线段树--线段树模板

1.线段树（最大值）线段树

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

const int MAXNODE = 1 << 19;

const int MAXN = 2e6 + 10;


struct NODE {
  int value;
  int left, right;
}node[MAXNODE];

int father[MAXN];

inline void BuildTree(int i, int left, int right) {
  node[i].left = left;
  node[i].right = right;
  node[i].value = 0;
  if (left == right) {
    father[left] = i;
    return;
  }
  BuildTree(i << 1, left, (int)(float(left + right) / 2.0));
  BuildTree((i << 1) + 1, (int)(floor(left + right) / 2.0) + 1,right);
}

inline void UpdateTree(int ri) {
  if (ri == 1) { return; }
  int fi = ri / 2;
  int a = node[fi << 1].value;
  int b = node[(fi << 1) + 1].value;
  node[fi].value = max(a, b);
  UpdateTree(ri / 2);
}

int Max;
inline void Query(int i, int l,int r) {
  if (node[i].left == l && node[i].right == r) {
    Max = max(Max, node[i].value);
    return;
  }
  i = i << 1;
  if (l <= node[i].right) {
    if (r <= node[i].right) {
      Query(i, l, r);
    }
    else {
      Query(i, l, node[i].right);
    }
  }
  i++;
  if (r >= node[i].left) {
    if (l >= node[i].left) { Query(i, l, r); }
    else {
      Query(i, node[i].left, r);
    }
  }
}

int main() {
  int n, m, g;
  ios::sync_with_stdio(false);
  while (cin >> n >> m) {
    BuildTree(1, 1, n);
    for (int i = 1; i <= n; i++) {
      cin >> g;
      node[father[i]].value = g;
      UpdateTree(father[i]);
    }
    string op;
    int a, b;
    while (m--) {
      cin >> op >> a >> b;
      if (op[0] == 'Q') {
        Max = 0;
        Query(1, a, b);
        cout << Max << endl;
      }
      else {
        node[father[a]].value = b;
        UpdateTree(father[a]);
      }
    }
  }
  return 0;
}

2.线段树（加和）模板 

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

const int MAXNODE = 1 << 19;

const int MAXN = 2e6 + 10;


struct NODE {
  int value;
  int left, right;
}node[MAXNODE];

int father[MAXN];

inline void BuildTree(int i, int left, int right) {
  node[i].left = left;
  node[i].right = right;
  node[i].value = 0;
  if (left == right) {
    father[left] = i;
    return;
  }
  BuildTree(i << 1, left, (int)(float(left + right) / 2.0));
  BuildTree((i << 1) + 1, (int)(floor(left + right) / 2.0) + 1, right);
}

inline void UpdateTree(int ri, int vl) {
  if (ri == 1) {
    node[ri].value += vl;
    return;
  }
  node[ri].value += vl;
  UpdateTree(ri / 2, vl);
}
int res;
inline void Query(int i, int l, int r) {
  if (node[i].left == l && node[i].right == r) {
    //Max = max(Max, node[i].value);
    res += node[i].value;
    return;
  }
  i = i << 1;
  if (l <= node[i].right) {
    if (r <= node[i].right) {
      Query(i, l, r);
    }
    else {
      Query(i, l, node[i].right);
    }
  }
  i++;
  if (r >= node[i].left) {
    if (l >= node[i].left) { Query(i, l, r); }
    else {
      Query(i, node[i].left, r);
    }
  }
}

int main() {
  int n, m, g, a, b;
  ios::sync_with_stdio(false);
  while (cin >> n >> m) {
    BuildTree(1, 1, n);
    for (int i = 1; i <= n; i++) {
      cin >> g;
      //node[father[i]].value = g;
      UpdateTree(father[i],g);
    }
    string op;
    while (m--) {
      cin >> op;
      if (op[0] == 'E') { break; }
      else if (op[0] == 'Q') {
        cin >> a >> b;
        res = 0;
        Query(1, a, b);
        cout << res << endl;
      }
      else if(op[0] == 'S')
      {
        cin >> a >> b;
        UpdateTree(father[a],-b);
      }
      else {
        cin >> a >> b;
        UpdateTree(father[a], b);
      }
    }
  }
  return 0;
}