SPOJ 1043 Can you answer these queries I 求任意區間最大連續子段和 線段樹

標籤：http   os   io   for   ar   amp   ef   on   

題目連結：點擊開啟連結

維護區間左起連續的最大和，右起連續的和。。

#include <cstdio>#include <iostream>#include <algorithm>#include <string.h>#include <math.h>#include <vector>#include <map>using namespace std;#define N 50050#define Lson(x) tree[x].l#define Rson(x) tree[x].r#define L(x) (x<<1)#define R(x) (x<<1|1)#define Sum(x) tree[x].sum#define Max(x) tree[x].max#define Lmax(x) tree[x].lmax#define Rmax(x) tree[x].rmaxstruct node{int l, r;int mid(){return (l+r)>>1;}int lmax, rmax, max, sum;}tree[N<<4];int n, a[N], Q;void push_down(int id){}void push_up(int id){Lmax(id) = max(Lmax(L(id)), Sum(L(id)) + Lmax(R(id)));Rmax(id) = max(Rmax(R(id)), Sum(R(id)) + Rmax(L(id)));Sum(id) = Sum(L(id)) + Sum(R(id));Max(id) = max(max(Max(L(id)), Max(R(id))), Rmax(L(id)) + Lmax(R(id)));}void updata_point(int val, int id){Lmax(id) = Rmax(id) = Max(id) = Sum(id) = val;}void build(int l, int r, int id){Lson(id) = l; Rson(id) = r;if(l == r){ updata_point(a[l], id);return;}int mid = tree[id].mid();build(l, mid, L(id));build(mid+1, r, R(id));push_up(id);}void updata(int pos, int val, int id){push_down(id);if(Lson(id) == Rson(id)){updata_point(val, id);return ;}int mid = tree[id].mid();if(mid < pos)updata(pos, val, R(id));else updata(pos, val, L(id));}int query_l(int l, int r, int id){push_down(id);if(l == Lson(id) && Rson(id) == r) return Lmax(id);int mid = tree[id].mid();if(mid < l)return query_l(l, r, R(id));else if(r <= mid)return query_l(l, r, L(id));int lans = query_l(l, mid, L(id)), rans = query_l(mid+1, r, R(id));return max(lans, Sum(L(id)) + rans);}int query_r(int l, int r, int id){push_down(id);if(l == Lson(id) && Rson(id) == r) return Rmax(id);int mid = tree[id].mid();if(mid < l)return query_r(l, r, R(id));else if(r <= mid)return query_r(l, r, L(id));int lans = query_r(l, mid, L(id)), rans = query_r(mid+1, r, R(id));return max(rans, Sum(R(id)) + lans);}int query(int l, int r, int id){push_down(id);if(l == Lson(id) && Rson(id) == r)return Max(id);int mid = tree[id].mid();if(mid < l)return query(l, r, R(id));else if(r<=mid)return query(l, r, L(id));int lans = query(l, mid, L(id)), rans = query(mid+1, r, R(id));int ans = max(lans, rans);return max(ans, query_r(l, mid, L(id)) + query_l(mid+1, r, R(id)));}int main(){while(~scanf("%d",&n)){for(int i = 1; i <= n; i++)scanf("%d",&a[i]);build(1, n, 1);scanf("%d",&Q);while(Q--){int l, r;scanf("%d %d",&l,&r);printf("%d\n", query(l, r, 1));}}return 0;}/*3 -1 2 311 2*/