线段树模板(区间和+区间最大值 + LAZY标记)

线段树模板

1. 区间和模板（线段树单点更新）

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#define maxn 50005using namespace std;//线段树模板struct node{    int l, r;    int sum; //根据情况sum的类型改为ll 或者 ull    int mid(){        return (l + r)>>1;    }};node tree[maxn*4];int value[maxn];char key[10];int idx, v;int cnt;void init_tree(int root, int l, int r){    tree[root].l = l;    tree[root].r = r;    if(l == r){         tree[root].sum = value[l];         return ;    }    init_tree(root<<1, l, (l + r)/2);    init_tree(root<<1|1, (l + r)/2 + 1, r);    tree[root].sum = tree[root<<1].sum + tree[root<<1|1].sum;}int query_tree(int root, int l, int r){    if(l<=tree[root].l&&r>=tree[root].r)         return tree[root].sum;    int mid=tree[root].mid(),ret=0;    if(l<=mid) ret+=query_tree(root<<1,l,r);           if(r>mid)  ret+=query_tree(root<<1|1,l,r);    return ret;}void update_tree(int root, int idx, int v){    if(tree[root].l == tree[root].r){        tree[root].sum = v;        return;    }    if(idx <= tree[root].mid()) update_tree(root<<1, idx, v);    else update_tree(root<<1|1, idx, v);    tree[root].sum = tree[root<<1].sum + tree[root<<1|1].sum;}

2.最大值模板

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;const int maxn = 200005;int n, m;struct node{    int l, r;    int MAX_VALUE; //表示区间最大值    int mid(){        return (l + r) >> 1;    }};node tree[maxn * 4];int value[maxn];void init(int root, int l, int r){    tree[root].l = l;    tree[root].r = r;    if(l == r){         tree[root].MAX_VALUE = value[l];         return;    }    int m = (l + r) >> 1;    init(root<<1, l, m);    init(root<<1|1, m+1, r);    tree[root].MAX_VALUE = max(tree[root<<1].MAX_VALUE, tree[root<<1|1].MAX_VALUE);}void update(int root, int idx, int v){    if(tree[root].l == tree[root].r){        tree[root].MAX_VALUE = v;        return;    }    if(idx <= tree[root].mid()) update(root<<1, idx, v);    else update(root<<1|1, idx, v);    tree[root].MAX_VALUE = max(tree[root<<1].MAX_VALUE, tree[root<<1|1].MAX_VALUE);}int query(int root, int l, int r){    if(l == tree[root].l && r == tree[root].r) return tree[root].MAX_VALUE;    int m = tree[root].mid();    if(l > m) return query(root<<1|1, l, r);    else if(r <= m) return query(root<<1, l, r);    else return max(query(root<<1, l, m), query(root<<1|1, m+1, r));}

3.LAZY标记模板(线段树区间更新)

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;const int maxn = 100010;struct node{    int l, r;    ll sum;    int mid(){        return (l + r)>>1;    }};node tree[maxn*4];ll value[maxn];ll visit[maxn*4]; //懒惰标记void pushDown(int root, int len){ //向下计算并更新线段树节点的之和    if(visit[root]){        visit[root<<1] += visit[root];        visit[root<<1|1] += visit[root];        tree[root<<1].sum += visit[root]*(len - (len>>1));        tree[root<<1|1].sum += visit[root]*(len>>1);        visit[root] = 0;    //每次更新完根节点需要还原    }}void pushUp(int root){  //向上计算节点之和(根节点 = 左子树值 + 右子树值)    tree[root].sum = tree[root<<1].sum + tree[root<<1|1].sum;}void init(int root, int l, int r){    tree[root].l = l;    tree[root].r = r;    if(l == r){        tree[root].sum = value[l];        return;    }    int m = (l + r) >> 1;    init(root<<1, l, m);    init(root<<1|1, m + 1, r);    // 等价于pushUp(root);    //tree[root].sum = tree[root<<1].sum + tree[root<<1|1].sum;    pushUp(root);}void update(int root, int op, int ed, int val){ //从[op, ed]区间    if(op == tree[root].l && ed == tree[root].r){        visit[root] += val;        tree[root].sum += (ll)((ed - op + 1) * val);        return;    }    if(tree[root].l == tree[root].r){        return;    }    int m = tree[root].mid();    pushDown(root, tree[root].r - tree[root].l + 1);    if(op > m) update(root<<1|1, op, ed, val);    else if(ed <= m)update(root<<1, op, ed, val);    else{        update(root<<1, op, m, val);        update(root<<1|1, m+1, ed, val);    }    //tree[root].sum = tree[root<<1].sum + tree[root<<1|1].sum;    pushUp(root);}ll query(int root, int l, int r){    if(tree[root].l == l && tree[root].r == r){        return tree[root].sum;    }    pushDown(root, tree[root].r - tree[root].l + 1); //向下更新节点值    int m = tree[root].mid();    if(l > m) return query(root<<1|1, l, r);    else if(r <= m) return query(root<<1, l, r);    else return query(root<<1, l, m) + query(root<<1|1, m + 1, r);}