segmentTreeSingleUpdate

#include <iostream>
#include <algorithm>
#include <climits>
using namespace std;



int inf = INT_MAX;

int segment[100]={0};

void constructTree(int number[],int start, int end, int pos){

    segment[pos]=0;

    if(start == end){

        segment[pos] = number[start];
        return;
    }

    int mid = (start+end) / 2;

    constructTree(number, start, mid, pos*2);
    constructTree(number, mid+1, end, pos*2+1);

    segment[pos] = min(segment[pos*2],segment[pos*2+1]);



    }

void updateSingle(int start, int end, int pos, int update, int value){

    if(update < start || end < update)
        return;

    if(update == start && update == end){

        segment[pos] = value;
        return;
    }



    if(start == end)
        return;


    int mid = (start + end)/2;

     updateSingle(start, mid, pos*2, update, value);
     updateSingle(start, mid, pos*2, update, value);

    segment[pos] = min(segment[pos*2], segment[pos*2+1]);




}



int query(int start, int end, int qstart, int qend, int pos){


        if(start >= qstart && end<=qend)
            return segment[pos];


        if(start > qend || end<qstart)
            return inf;

    int mid = (start + end) /2;
    int x = query(start,mid, qstart, qend, pos*2);
    int y = query(mid+1, end, qstart, qend, pos*2+1);

    return min(x,y);

}


int main(int argc, char **argv)
{


    /*                 0  1   2    3   3 5 6  7  */
    int number[8] = {1,2,3,4,5,6,7,8};

    int size = sizeof(number)/sizeof(number[0])-1;


    constructTree(number,0,size, 1);


    //for(int  i=0; i<20; i++)

        //cout<<i<<":"<<segment[i]<<" \n";

    for(int i=1; i<15; i++)
        cout<<i<<":"<<segment[i]<<" ";
    cout<<endl;

    updateSingle(0,7,1, 0, -111111);

    for(int i=1; i<15; i++)
        cout<<i<<":"<<segment[i]<<" ";

    /*
    cout<<query(0, size, 0, 7,1)<<"\n";
    cout<<query(0, size, 0, 3,1)<<"\n";
    cout<<query(0, size, 4, 7,1)<<"\n";
    cout<<query(0, size, 1, 3,1)<<"\n";

    */



    return 0;
}