#include <stdio.h>
#include <vector>
#include <math.h>
#include <iostream>
#include <stdlib.h>

struct slot_t {
    /** relative position */
    float x, y ;
} ;

float ofDist(float x1, float y1, float x2, float y2) {
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

//--------------------------------------------------------------
int findTop() {

    float dist[3];
    dist[0] = ofDist(.25, .75, .50, .12);
    dist[1] = ofDist(.50, .12, .75, .75);
    dist[2] = ofDist(.25, .75, .75, .75);

    float dist0to1 = dist[0];
    std::cout << "dist0to1: " << dist0to1 << "\n";
    float dist1to2 = dist[1];
    std::cout << "dist1to2: " << dist1to2 << "\n";
    float dist0to2 = dist[2];
    std::cout << "dist0to2: " << dist0to2 << "\n";

    float diff01m02 = abs(dist0to1 - dist0to2);
    std::cout << "diff01m02: " << diff01m02 << "\n";
    float diff02m12 = abs(dist0to2 - dist1to2);
    std::cout << "diff01m02: " << diff01m02 << "\n";
    float diff01m12 = abs(dist0to1 - dist1to2);
    std::cout << "diff01m02: " << diff01m02 << "\n";

    if (diff01m02 < diff02m12 && diff01m02 < diff01m12) {
            return 0;
    }
    else if (diff01m12<diff01m02 && diff01m12<diff02m12) {
            return 1;
    }
    else if (diff02m12<diff01m02 && diff02m12<diff01m12) {
            return 2;
    }
    return 99;
}

int main (){

    std::cout << "findTop: " << findTop() << "\n";

    return 0;


}


output:

dist0to1: 0.677791
dist1to2: 0.677791
dist0to2: 0.5
diff01m02: 0
diff01m02: 0
diff01m02: 0
findTop: 99