c/c++语言开发共享SPOJ1043 GSS1(线段树)

/*    */  #include<cstdio>  #include<cstring>  #include<algorithm>  #include<map>  #include<vector>  #include<set>  #include<queue>  #include<cmath>  #include<ext/pb_ds/assoc_container.hpp>  #include<ext/pb_ds/hash_policy.hpp>  #define pair pair<int, int>  #define mp(x, y) make_pair(x, y)  #define fi first  #define se second  //#define int long long   #define ll long long   #define rg register   #define sc(x) scanf("%d", &x);  #define pt(x) printf("%d ", x);  #define db(x) double x   #define rep(x) for(int i = 1; i <= x; i++)  #define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1<<22, stdin), p1 == p2) ? eof : *p1++)  char buf[(1 << 22)], *p1 = buf, *p2 = buf;  char obuf[1<<24], *o = obuf;  #define os  *o++ = 'n';  using namespace std;  using namespace __gnu_pbds;  const int maxn = 50001, inf = 1e9 + 10, mod = 1e9 + 7;  const double eps = 1e-9;  inline int read() {      char c = getchar(); int x = 0, f = 1;      while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}      while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();      return x * f;  }  void print(int x) {      if(x > 9) print(x / 10);      *o++ = x % 10 + '0';  }  #define ls k << 1  #define rs k << 1 | 1  int n, m;  int a[maxn];  struct node {      int l, r, lmx, rmx, mx, sum;  }t[maxn << 2];  void update(int k) {      t[k].sum = t[ls].sum + t[rs].sum;      t[k].mx = max(t[ls].mx, t[rs].mx);      t[k].mx = max(t[k].mx, t[ls].rmx + t[rs].lmx);      t[k].rmx = max(t[rs].rmx, t[rs].sum + t[ls].rmx);      t[k].lmx = max(t[ls].lmx, t[ls].sum + t[rs].lmx);  }  void build(int k, int ll, int rr) {      t[k] = (node) {ll, rr, 0, 0, 0};      if(ll == rr) {          t[k].lmx = t[k].rmx = t[k].mx = t[k].sum = a[ll];           return ;      }      int mid = ll + rr >> 1;      build(ls, ll, mid);      build(rs, mid + 1, rr);      update(k);  }  node merge(node a, node b) {      node now;      now.sum = a.sum + b.sum;      now.mx = max(a.mx, b.mx);      now.mx = max(now.mx, a.rmx + b.lmx);      now.rmx = max(b.rmx, b.sum + a.rmx);      now.lmx = max(a.lmx, a.sum + b.lmx);      //    printf("%d %d %d %dn", now.mx, now.lmx, now.rmx, now.sum);      return now;  }  node query(int k, int ll, int rr) {      node ans = (node) {0, 0, 0, 0, 0};      if(ll <= t[k].l && t[k].r <= rr) return t[k];      int mid = t[k].l + t[k].r >> 1;      /*if(ll <= mid) ans = query(ls, ll, rr);      if(rr  > mid) ans = merge(ans, query(rs, ll, rr)); wa!*/      if(ll > mid) return query(rs, ll, rr);      else if(rr <= mid) return query(ls, ll, rr);      else return merge(query(ls, ll, rr), query(rs, ll, rr));      return ans;  }  main() {      //freopen("a.in", "r", stdin);      n = read();      for(int i = 1; i <= n; i++) a[i] = read();      build(1, 1, n);          int m = read();      while(m--) {          int x = read(), y = read();          printf("%dn", query(1, x, y).mx);      }      //fwrite(obuf, o-obuf, 1 , stdout);      return 0;  }  /*  5  -10 12 1 -45 134  5  1 5  2 3  4 5  1 4  3 5  */