HackerEarth Update And Query problem solution

In this HackerEarth Update And Query problem, Deepankar loves to play with the arrays a lot. Today, he has an array A of N integers. He has to fulfill M operations. Each operation has one of the following two types:

U X Y : Update the value at the Xth index of the array with Y.

Q X C : Calculate the length of the longest subarray that starts at Xth index and satisfy following inequality

A[X]-C ≤ V ≤ A[X] + C

Where V is any value from the chosen subarray.

Deepankar is facing difficulty in maintaining the efficiency of the operations. Can you help him in accomplishing this task efficiently.

HackerEarth Update And Query problem solution.

#include <bits/stdc++.h>
using namespace std ;

#define MAXN 100001
#define ft first
#define sd second 


int N,M,A[MAXN],STMX[4*MAXN],STMN[4*MAXN],X,Y,C;
char str[10] ;

void buildst(int idx,int ss,int se){

    if(ss == se){
        STMX[idx] = A[ss] ;
        STMN[idx] = A[ss] ;
        return ;
    }
    int mid = (ss + se)/2;
    buildst(2*idx,ss,mid) ;
    buildst(2*idx+1,mid+1,se) ;
    STMX[idx] = max(STMX[2*idx],STMX[2*idx+1]) ;
    STMN[idx] = min(STMN[2*idx],STMN[2*idx+1]) ;
}

void update(int idx,int ss,int se,int val,int pos){

    if(ss == se){
        STMX[idx] = val ;
        STMN[idx] = val ;
        return ;
    }

    int mid = (ss + se)/2 ;
    if(pos <= mid)
        update(2*idx,ss,mid,val,pos) ;
    else
        update(2*idx+1,mid+1,se,val,pos) ;
    
    STMX[idx] = max(STMX[2*idx],STMX[2*idx+1]) ;
    STMN[idx] = min(STMN[2*idx],STMN[2*idx+1]) ;
}

pair<int,int> query(int idx,int ss,int se,int l,int r){

    pair<int,int> ret ;
    if(l > se || r < ss){
        ret.ft = INT_MIN ;
        ret.sd = INT_MAX ;
        return ret ;    
    }
    if(l <= ss && se <= r){
        return make_pair(STMX[idx],STMN[idx]) ;
    }
    int mid = (ss + se)/2 ;
    pair<int,int> left ,right ;
    left  = query(2*idx,ss,mid,l,r) ;
    right = query(2*idx+1,mid+1,se,l,r) ;
    return make_pair(max(left.ft,right.ft),min(left.sd,right.sd)) ;
}

bool check(int L,int R,int C){
    pair<int,int> ret ;
    ret = query(1,1,N,L,R) ;
    return ((ret.ft-A[L] <= C) && (A[L]-ret.sd <= C)) ;
}

void solve(int X,int C){

    int V1,V2 ;
    V1 = V2 = -1 ;

    if(C >= 0){
        int low , high , mid ;
        low = X ;
        high = N ;
        while(low <= high){
            mid = (low + high)/2 ;
            bool f = check(X,mid,C) ;
            if( f && (mid == N || check(X,mid+1,C) == 0)){
                break ;
            }else if(f){
                low = mid+1 ;
            }else{
                high = mid-1 ;
            }
        }
        V1 = mid-X+1 ;
        pair<int,int> ret = query(1,1,N,X,mid) ; 
        V2 = max(ret.ft-A[X],A[X]-ret.sd) ;
    }
    printf("%d %d\n",V1,V2) ;   
}
int main(){

    scanf("%d%d",&N,&M) ;
    assert(N >= 1 && N <= 100000) ;
    assert(M >= 1 && M <= 200000) ;
    for(int i=1;i<=N;i++){
        scanf("%d",&A[i]) ;
        assert(A[i] >= 1 && A[i] <= 1000000000) ;   
    }   
    buildst(1,1,N) ;
    while(M--){
        scanf("%s",str+1) ;
        if(str[1] == 'U'){
            scanf("%d%d",&X,&Y) ;
            A[X] = Y ;
            update(1,1,N,Y,X) ;
    
        }else if(str[1] == 'Q'){
            scanf("%d%d",&X,&C) ;
            solve(X,C) ;            
        }else{
            assert(0) ;
        }
    }
    return 0 ;
}