线段树

测例：

30 5
3 4 6 8 4 1 4 12 4 5 1234 34 54 213 12 3 6456 121 434 12 3 2 1234 234 234 45 1 34 6 234
1 3
4 8
23 29
1 25
13 29

#include <iostream>
#include <vector>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

std::vector<int> v;
int len,queNum;

struct node
{
node* left;
node* right;
int value;
int rangel;
int ranger;
};

node* root;

void input(){
cin >> len >> queNum;
for (int i = 0 ; i < len; i++){
int a;
cin >> a;
v.push_back(a);
}
root = new node();
}

int initTree(int ss, int ee, node* r){
//cout << ss << ","<<ee<<endl;
r->rangel = ss;
r->ranger = ee;
int maxx;
if (ss == ee){
r->value = v[ss];
r->left = NULL;
r->right = NULL;
return r->value;
}

int middle = (r->rangel+r->ranger)/2;
node* ll = new node();
node* rr = new node();

maxx = max( initTree(ss,middle,ll) , initTree(middle+1,ee,rr) );
r->value = maxx;
r->left = ll;
r->right= rr;

return maxx;
}

int baoli(int ss, int ee){
int maxx = -1;
for (int i = ss-1; i< ee ; i++){
if (v[i] > maxx){
maxx = v[i];
}
}
return maxx;
}

int query(int ss, int ee, node* r){

if (r->rangel == ss && r->ranger == ee){
return r->value;
}

int middle = (r->rangel+r->ranger)/2;
if (ee <= middle){
return query(ss,ee,r->left);
}
if (ss > middle){
return query(ss,ee,r->right);
}

return max( query(ss,middle,r->left) , query(middle+1,ee,r->right) );
}

void output(){
while(queNum--){
int ss,ee;
cin >> ss >> ee;
int bb = baoli(ss,ee);
int qq = query(ss-1,ee-1,root);
if (bb != qq){
cout << "wrong! bb = "<<bb << " qq = "<<qq<<endl;
}
else{
cout << "Right res="<<qq<<endl;
}
}

}

int main(){
input();

initTree(0,len-1,root);

output();

return 0;
}