My solution for UVA 12532

uva_12532.cpp

#include <iostream>
#include <vector>
#include <string>
using namespace std;

class SegmentTree {
private:
    int n;
    vector<char> st;

    int left(int i) { return i<<1; }
    int right(int i) { return (i<<1)+1; }

    int build(int L, int R, int idx, const vector<int> &A) {
	if(L == R) st[idx] = getSign(A[L]);
	else {
	    int left_val = build(L, (L+R)/2, left(idx), A);
	    int right_val = build(((L+R)/2)+1, R, right(idx), A);
	    st[idx] = combine(left_val, right_val);
	}
	return st[idx];
    }

    char getSign(int i) {
	return (i > 0 ? '+' : (i == 0 ? '0' : '-'));
    }

    char combine(char i, char j) {
	if(i == '0' || j == '0') return '0';
	if(i == j) return '+';
	return '-';
    }

    char query(int i, int j, int L, int R, int idx) {
	if(j < L || R < i) return -1;
	if(i <= L && R <= j) return st[idx];

	char left_val = query(i, j, L, (L+R)/2, left(idx));
	char right_val = query(i, j, ((L+R)/2)+1, R, right(idx));

	if(left_val == -1) return right_val;
	if(right_val == -1) return left_val;
	return combine(left_val, right_val);
    }

    char update(int i, int v, int L, int R, int idx) {
	if(i < L || i > R) return st[idx];
	if(L == R && L == i) {
	    st[idx] = getSign(v);
	    return st[idx];
	}
	char left_val = update(i, v, L, (L+R)/2, left(idx));
	char right_val = update(i, v, ((L+R)/2)+1, R, right(idx));
	return st[idx] = combine(left_val, right_val);
    }

public:
    SegmentTree(vector<int> &A) {
	n = A.size();
	st.assign(4*n, 0);
	build(0, n-1, 1, A);
    }

    char query(int i, int j) {
	return query(i, j, 0, n-1, 1);
    }

    void update(int i, int v) {
	update(i, v, 0, n-1, 1);
    }
};

int n, k;
vector<int> a;
int main() {
    while(cin >> n >> k) {
	a.resize(n);
	for(auto &x : a) cin >> x;
	SegmentTree st(a);
	string ans = "";
	while(k--) {
	    char c; int a, b;
	    cin >> c >> a >> b;
	    if(c == 'C') st.update(a-1, b);
	    else ans += st.query(a-1, b-1);
	}
	cout << ans << '\n';
    }
	
    return 0;
}