MaxEl of seq. (TREE) максимал.эл.последовательности

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int *tree_data = 0;

#define min(x,y) (x<y?x:y)
#define max(x,y) (x>y?x:y)

#define TREE_FUNCT(x,y) (max(x,y))

void build (int a[], int v, int tl, int tr) {
        if (tl == tr)
        tree_data[v] = a[tl];
    else {
        int tm = (tl + tr) / 2;
        build (a, v*2, tl, tm);
        build (a, v*2+1, tm+1, tr);
        tree_data[v] = TREE_FUNCT(tree_data[v*2],tree_data[v*2+1]);
    }
}


int compute (int v, int tl, int tr, int l, int r, int* value) {
    int tm;
    int lvalue,rvalue;
    int lresult,rresult;

    if (l > r)
        return 0;
    if (l == tl && r == tr){
        *value = tree_data[v];
        return 1;
    }

    tm = (tl + tr) / 2;

    lresult = compute (v*2, tl, tm, l, min(r,tm),&lvalue);
    rresult = compute (v*2+1, tm+1, tr, max(l,tm+1), r,&rvalue);

    if ((lresult>0)&&(rresult>0)){
        *value = TREE_FUNCT(lvalue,rvalue);
    } else{
        if (lresult)
            *value = lvalue;
        if (rresult)
            *value = rvalue;
    }



    return 1;
}

void update (int v, int tl, int tr, int pos, int new_val) {
    if (tl == tr)
        tree_data[v] = new_val;
    else {
        int tm = (tl + tr) / 2;
        if (pos <= tm)
            update (v*2, tl, tm, pos, new_val);
        else
            update (v*2+1, tm+1, tr, pos, new_val);
        tree_data[v] = TREE_FUNCT(tree_data[v*2],tree_data[v*2+1]);
    }
}

int main(int argc,char** argv){
    int* data = 0;
    int i,N;
    int ops_count;

    scanf("%d",&N);

    data = (int*)malloc(sizeof(int) * N);
    tree_data = (int*)malloc(N * 4 * sizeof(int));


    for (i=0;i!=N;i++)
        scanf("%d",&(data[i]));

    build(data,1,0,N-1);



    scanf("%d",&ops_count);
    while(ops_count){
        char command[255];
        int l1,l2;

        memset(command,0,255);
        scanf("%s",command);
        scanf("%d",&l1);
        scanf("%d",&l2);

        if (command[0]=='M'){

            if (l2 <= N-1){
                int result;
                compute(1,0,N-1,l1,l2,&result);
                printf("%d\n",result);
            }
        }
        if (command[0]=='U'){
            if (l1 <= N-1){
                update(1,0,N-1,l1,l2);
            }

        }

        ops_count--;
    }


    free(tree_data);
    free(data);
}