RMQ:
1 #include <bits/stdc++.h> 2 #define rep(i,a,b) for(int i = a;i <= b;++ i) 3 #define per(i,a,b) for(int i = a;i >= b;-- i) 4 #define mem(a,b) memset((a),(b),sizeof((a))) 5 #define FIN freopen("in.txt","r",stdin) 6 #define IO ios_base::sync_with_stdio(0),cin.tie(0) 7 #define pb push_back 8 using namespace std; 9 typedef long long LL; 10 typedef pair<int, int> PIR; 11 const int N = 1e6+5; 12 13 int n, m, l, r, mm[N], a[N], dp[N][20]; 14 15 void RMQ_init(){ 16 rep(i, 1, n) dp[i][0] = a[i]; 17 for(int j = 1; (1<<j) <= n; ++j){ 18 for(int i = 0; i+(1<<j)-1 <= n; ++i) 19 dp[i][j] = min(dp[i][j-1], dp[i+(1<<(j-1))][j-1]); 20 } 21 } 22 int RMQ(int l, int r){ 23 int k = 0; 24 while(1<<(k+1) <= r-l+1) k++; 25 return min(dp[l][k], dp[r-(1<<k)+1][k]); 26 } 27 int main() 28 {//IO; 29 //FIN; 30 scanf("%d", &n); 31 rep(i, 1, n) scanf("%d", &a[i]); 32 RMQ_init(); 33 scanf("%d", &m); 34 while(m--){ 35 scanf("%d%d", &l, &r); 36 printf("%d\n", RMQ(l, r)); 37 } 38 return 0; 39 }
线段树：
1 #include <bits/stdc++.h> 2 #define rep(i,a,b) for(int i = a;i <= b;++ i) 3 #define per(i,a,b) for(int i = a;i >= b;-- i) 4 #define mem(a,b) memset((a),(b),sizeof((a))) 5 #define FIN freopen("in.txt","r",stdin) 6 #define IO ios_base::sync_with_stdio(0),cin.tie(0) 7 #define pb push_back 8 #define mid ((l+r)>>1) 9 #define ls (id<<1) 10 #define rs ((id<<1)|1) 11 using namespace std; 12 typedef long long LL; 13 typedef pair<int, int> PIR; 14 const int N = 1e6+5; 15 16 int n, m, op, x, y, a[N]; 17 18 struct Node{ 19 int minn; 20 }node[N*4]; 21 void pushUp(int id, int l, int r){ 22 node[id].minn = min(node[ls].minn, node[rs].minn); 23 } 24 void build(int id, int l, int r){ 25 if(l == r) { node[id].minn = a[l]; return; } 26 build(ls, l, mid); 27 build(rs, mid+1, r); 28 pushUp(id, l, r); 29 } 30 void update(int id, int l, int r, int p, int val){ 31 if(l == r && l == p) { node[id].minn = val; return; } 32 if(p <= mid) update(ls, l, mid, p, val); 33 else update(rs, mid+1, r, p, val); 34 pushUp(id, l, r); 35 } 36 int query(int id, int l, int r, int ql, int qr){ 37 if(l == ql && r == qr) return node[id].minn; 38 if(qr <= mid) query(ls, l, mid, ql, qr); 39 else if(ql > mid) query(rs, mid+1, r, ql, qr); 40 else{ 41 return min(query(ls, l, mid, ql, mid), query(rs, mid+1, r, mid+1, qr)); 42 } 43 } 44 int main() 45 {IO; 46 //FIN; 47 scanf("%d", &n); 48 rep(i, 1, n) scanf("%d", &a[i]); 49 build(1, 1, n); 50 scanf("%d", &m); 51 while(m--){ 52 scanf("%d %d", &x, &y); 53 printf("%d\n", query(1, 1, n, x, y)); 54 } 55 return 0; 56 }
