HDU 1754 I Hate It (线段树)
简单的线段树，多余的就不解释了。
1 #include<cstdio> 2 #include<iostream> 3 4 using namespace std; 5 #define INF 0xffffff0 6 #define max(a,b) (a>b?a:b) 7 #define min(a,b) (a<b?a:b) 8 struct Node 9 { 10 int maxV; 11 int L, R; 12 int Mid() 13 { 14 return (L+R)/2; 15 } 16 }Tree[800010]; 17 int maxV = 0; 18 void BuildTree(int root,int L,int R); 19 void Query(int root,int s,int e); 20 void Insert(int root,int i,int v);//第i个数 为 V 21 22 int main() 23 { 24 int N, M; 25 while(scanf("%d%d",&N,&M) != EOF) 26 { 27 int k; 28 BuildTree(0,1,N); 29 for(int i = 1; i <= N; i++) 30 { 31 scanf("%d",&k); 32 Insert(0,i,k); 33 } 34 while(M--) 35 { 36 int s, e; 37 char str[2]; 38 maxV = 0; 39 scanf("%s%d%d",str,&s,&e); 40 if(str[0] == 'Q') 41 { 42 Query(0,s,e); 43 printf("%d\n",maxV); 44 } 45 else 46 Insert(0,s,e); 47 } 48 } 49 return 0; 50 } 51 52 void BuildTree(int root,int L,int R) 53 { 54 Tree[root].L = L; 55 Tree[root].R = R; 56 Tree[root].maxV = 0; 57 if(L != R) 58 { 59 BuildTree(root*2+1,L,Tree[root].Mid()); 60 BuildTree(root*2+2,Tree[root].Mid()+1,R); 61 } 62 } 63 void Query(int root,int s,int e) 64 { 65 if(Tree[root].maxV <= maxV) 66 return ; 67 if(Tree[root].L == s && Tree[root].R == e) 68 { 69 maxV = max(Tree[root].maxV, maxV); 70 return ; 71 } 72 if(e <= Tree[root].Mid()) 73 Query(root*2+1,s, e); 74 else if( s > Tree[root].Mid()) 75 Query(root*2+2,s, e); 76 else 77 { 78 Query(root*2+1,s,Tree[root].Mid()); 79 Query(root*2+2,Tree[root].Mid()+1,e); 80 } 81 } 82 void Insert(int root,int i,int v)//第i个数 为 V 83 { 84 if(Tree[root].L == Tree[root].R) 85 { 86 Tree[root].maxV = v; 87 return ; 88 } 89 Tree[root].maxV = max(v,Tree[root].maxV); 90 if(i <= Tree[root].Mid()) 91 Insert(root*2+1,i,v); 92 else 93 Insert(root*2+2,i,v); 94 }
