[zoj3632]线段树的应用

题意：f[i] = min(f[i+L]~f[i+R]) + x，计算f数组。从大到小计算即可，用线段树维护一下。

 #pragma comment(linker, "/STACK:10240000,10240000")
 
 #include <iostream>
 #include <cstdio>
 #include <algorithm>
 #include <cstdlib>
 #include <cstring>
 #include <map>
 #include <queue>
 #include <deque>
 #include <cmath>
 #include <vector>
 #include <ctime>
 #include <cctype>
 #include <set>
 
 using namespace std;
 
 #define mem0(a) memset(a, 0, sizeof(a))
 #define lson l, m, rt << 1
 #define rson m + 1, r, rt << 1 | 1
 #define define_m int m = (l + r) >> 1
 #define rep(a, b) for (int a = 0; a < b; a++)
 #define rrep(a, b) for (int a = (b - 1); a >= 0; a--)
 #define all(a) (a).begin(), (a).end()
 #define lowbit(x) ((x) & (-(x)))
 #define constructInt4(name, a, b, c, d) name(int a = 0, int b = 0, int c = 0, int d = 0): a(a), b(b), c(c), d(d) {}
 #define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {}
 #define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {}
 #define pc(a) putchar(a)
 #define ps(a) printf("%s", a)
 #define pd(a) printf("%d", a)
 #define sd(a) scanf("%d", &a)
 
 typedef double db;
 typedef long long LL;
 typedef pair<int, int> pii;
 typedef multiset<int> msi;
 typedef set<int> si;
 typedef vector<int> vi;
 typedef map<int, int> mii;
 
 const int dx[] = {, , , -, , , -, -};
 const int dy[] = {, , -, , -, , , -};
 const int maxn =  * 1e4 + ;
 const int maxm = 1e5 + ;
 const int minv = 1e7 + ;
 const int max_val = 1e6 + ;
 const int MD = 1e9 +;
 const LL INF = 1e15;
 const double PI = acos(-1.0);
 const double eps = 1e-;
 
 template<class T> T gcd(T a, T b) { return b == ? a : gcd(b, a % b); }
 
 struct SegTree {
     LL minv[maxn << ];
     void build(int l, int r, int rt) {
         minv[rt] = INF;
         if (l == r) return ;
         define_m;
         build(lson);
         build(rson);
     }
     LL get(int L, int R, int l, int r, int rt) {
         if (L <= l && r <= R) return minv[rt];
         define_m;
         LL res = INF;
         if (L <= m) res = min(res, get(L, R, lson));
         if (R > m) res = min(res, get(L, R, rson));
         return res;
     }
     void update(int p, LL x, int l, int r, int rt) {
         if (l == r) {
             minv[rt] = x;
             return ;
         }
         define_m;
         if (p <= m) update(p, x, lson);
         else update(p, x, rson);
         minv[rt] = min(minv[rt << ], minv[rt <<  | ]);
     }
 };
 
 SegTree st;
 int cost[maxn], len[maxn];
 int main() {
     //freopen("in.txt", "r", stdin);
     int n;
     while (cin >> n) {
         rep(i, n) sd(cost[i]);
         rep(i, n) sd(len[i]);
         st.build(, n, );
         rrep(i, n) {
             LL x = cost[i];
             if (i + len[i] < n) x  += st.get(i + , i +  + len[i], , n, );
             st.update(i + , x, , n, );
         }
         cout << st.get(, , , n, ) << endl;
     }
     return ;
 }