线段树（lazy标记）-- 模板

 int a[MAXN], ans[MAXN << ], lazy[MAXN << ];
 void PushUp(int rt) {
     ans[rt] = ans[rt << ] + ans[rt <<  | ];
 }
 void PushDown(int rt, int ln, int rn) { //ln表示左子树元素结点个数，rn表示右子树结点个数
     if (lazy[rt]) {
         lazy[rt << ] += lazy[rt];
         lazy[rt <<  | ] += lazy[rt];
         ans[rt << ] += lazy[rt] * ln;
         ans[rt <<  | ] += lazy[rt] * rn;
         lazy[rt] = ;
     }
 }
 //建树Build(1,n,1)
 void Build(int l, int r, int rt) {
     if (l == r) {
         ans[rt] = a[l];
         return;
     }
     int mid = (l + r) >> ;
     Build(l, mid, rt << );
     Build(mid + , r, rt <<  | );
     PushUp(rt);
 }
 //点更新Add(L,C,1,n,1)
 void Add(int L, int C, int l, int r, int rt) {
     if (l == r) {
         ans[rt] += C;
         return;
     }
     int mid = (l + r) >> ;
     //PushDown(rt,mid-l+1,r-mid); 若既有点更新又有区间更新，需要这句话
     if (L <= mid)
         Add(L, C, l, mid, rt << );
     else
         Add(L, C, mid + , r, rt <<  | );
     PushUp(rt);
 }
 //区间更新Upadate(L,R,C,1,n,1)
 void Update(int L, int R, int C, int l, int r, int rt) {
     if (L <= l && r <= R) {
         ans[rt] += C * (r - l + );
         lazy[rt] += C;
         return;
     }
     int mid = (l + r) >> ;
     PushDown(rt, mid - l + , r - mid);
     if (L <= mid)
         Update(L, R, C, l, mid, rt << );
     if (R > mid)
         Update(L, R, C, mid + , r, rt <<  | );
     PushUp(rt);
 }
 //区间查询Query(L,R,1,n,1)
 LL Query_sum(int L, int R, int l, int r, int rt) {
     if (L <= l && r <= R)
         return ans[rt];
     int mid = (l + r) >> ;
     PushDown(rt, mid - l + , r - mid); //若更新只有点更新，不需要这句
     LL ANS = ;
     if (L <= mid)
         ANS += Query_sum(L, R, l, mid, rt << );
     if (R > mid)
         ANS += Query_sum(L, R, mid + , r, rt <<  | );
     return ANS;
 }
 //区间最大值
 int Query_max(int L, int R, int l, int r, int rt) {
     if (L <= l&&R <= r)
         return ans[rt];
     int mid = (l + r) >> ;
     PushDown(rt, mid - l + , r - mid);
     int ANS = ;
     if (L <= mid) ANS = max(ANS, Query_max(L, R, l, mid, rt << ));
     if (R > mid) ANS = max(ANS, Query_max(L, R, mid + , r, rt <<  | ));
     return ANS;
 }
 //单点查询
 int Query(int L, int R, int l, int r, int rt) {
     if (L == l&&R == r)
         return ans[rt];
     int mid = (l + r) >> ;
     PushDown(rt, mid - l + , r - mid);
     int ANS = ;
     if (L <= mid)
         ANS = Query(L, R, l, mid, rt << );
     if (R > mid)
         ANS = Query(L, R, mid + , r, rt <<  | );
     return ANS;
 }