C++ :: Selection Of Interesting Point From Long List

I have some codes which are not efficient enough to get the answer faster.

Q: Tom is looking for a car with high miles per gallon and high horse power.For example:P1--Toyota with MPG=51,HP=134, the P2--Honda with MPG=40,HP=110, P3--Ford Fusion with MPG=41,HP=191,P4--Nissan with MPG=35,HP=195,P5--Volkswagen with MPG=30,HP=140

Since,p2 is worse than p1(in terms of MPG,HP) and p5 worse than p4(MPG,HP), thus they are cancelled. The leftover 3 cars are considered interesting cars.Tom wish to find all interesting cars from the list but there's too many of them. Thus write a program to find this list as fast as possible.(C++)

int SimpleAlgo2 (int &n, int &d, vector< vector<float> > &point) {
vector<bool> isBest(n+10, true);
for (int i=0; i<n; i++) {
for (int j=0; j<n; j++) {

// We will check if point[i] is strictly worse than point[j]
// no need to check if we already know that point[i] is not the best
if (isBest[i]) {

[Code] ....