BZOJ1699: [Usaco2007 Jan]Balanced Lineup排队 - 线段树

description

查询区间最大和最小

题解

线段树

愉悦身心啊

代码

 #include<cstring>
 #include<cstdio>
 #include<algorithm>
 #define rd read()
 #define lson nd << 1
 #define rson nd << 1 | 1
 using namespace std;

 const int N = 1e5;
 const int inf = ~0U >> ;

 int MAX[N << ], MIN[N << ], a[N], q, n;

 int read() {
     int X = , p = ; char c = getchar();
     for(; c > '' || c < ''; c = getchar()) if(c == '-') p = -;
     for(; c >= '' && c <= '';c = getchar()) X = X *  + c - '';
     return X * p;
 }

 void print(int x) {
     if(x < ) putchar('-'), x = -x;
     if(x >= ) print(x / );
     putchar(x %  + '');
 }

 void update(int nd) {
     MIN[nd] = min(MIN[lson], MIN[rson]);
     MAX[nd] = max(MAX[lson], MAX[rson]);
 }

 void build(int l, int r, int nd) {
     if(l == r) {
         MIN[nd] = MAX[nd] = a[l];
         return;
     }
     int mid = (l + r) >> ;
     build(l, mid, lson);
     build(mid + , r, rson);
     update(nd);
 }

 int query_max(int L, int R, int l, int r, int nd) {
     if(L <= l && r <= R) return MAX[nd];
     int mid = (l + r) >> , tmp = ;
     if(L <= mid) tmp = max(tmp, query_max(L, R, l, mid, lson));
     if(mid < R) tmp = max(tmp, query_max(L, R, mid + , r, rson));
     return tmp;
 }

 int query_min(int L, int R, int l, int r, int nd) {
     if(L <= l && r <= R) return MIN[nd];
     int mid = (l + r) >> , tmp = inf;
     if(L <= mid) tmp = min(tmp, query_min(L, R, l, mid, lson));
     if(mid < R) tmp = min(tmp, query_min(L, R, mid + , r, rson));
     return tmp;
 }

 int main()
 {
     n = rd; q = rd;
     for(int i = ; i <= n; ++i) a[i] = rd;
     build(, n, );
     for(int i = ; i <= q; ++i) {
         int l = rd, r = rd;
         int mx = query_max(l, r, , n, ), mn = query_min(l, r, , n, );
         print(mx - mn);
         putchar('\n');
     }
 }