http://acm.hdu.edu.cn/showproblem.php?pid=1754
依次比较左右子节点 父节点存最大值
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1 #include <iostream> 2 #include<cstdio> 3 #include<string.h> 4 #define MAX 200000 5 using namespace std; 6 int s[MAX*4],a; 7 void push(int w) 8 { 9 if(s[2*w]>s[2*w+1]) 10 s[w] = s[2*w]; 11 else 12 s[w] = s[2*w+1]; 13 } 14 void build(int l,int r,int w) 15 { 16 if(l==r) 17 { 18 scanf("%d",&a); 19 s[w] = a; 20 return ; 21 } 22 int m = (l+r)/2; 23 build(l,m,2*w); 24 build(m+1,r,2*w+1); 25 push(w); 26 } 27 void add(int p,int da,int l,int r,int w) 28 { 29 if(l==r) 30 { 31 s[w] = da; 32 return; 33 } 34 int m = (l+r)/2; 35 if(p<=m) 36 add(p,da,l,m,2*w); 37 else 38 add(p,da,m+1,r,2*w+1); 39 push(w); 40 } 41 int search(int a,int b,int l,int r,int w) 42 { 43 if(a<=l&&b>=r) 44 { 45 return s[w]; 46 } 47 int m = (l+r)/2,re = 0; 48 if(a<=m) 49 re = max(re,search(a,b,l,m,2*w)); 50 if(b>m) 51 re = max(re,search(a,b,m+1,r,2*w+1)); 52 return re; 53 } 54 int main() 55 { 56 int i,j,k1,k2,n,m; 57 char c; 58 while(scanf("%d%d",&n,&m)!=EOF) 59 { 60 build(1,n,1); 61 while(m--) 62 { 63 scanf("%*c%c",&c); 64 if(c=='Q') 65 { 66 scanf("%d %d",&k1,&k2); 67 printf("%d\n",search(k1,k2,1,n,1)); 68 } 69 else 70 { 71 scanf("%d %d",&k1,&k2); 72 add(k1,k2,1,n,1); 73 } 74 } 75 } 76 return 0; 77 }