1496. Path Crossing

typedef pair<int, int> step_type;

class Solution {
public:
    bool isPathCrossing(string path) {
        int x = 0;
        int y = 0;
        vector<step_type> step;
        step_type default_step(0, 0);
        step.push_back(default_step);
        for(int n = 0; n < path.size(); n++) {
            if (path[n] == 'N') {
                y = y + 1;
            } else if (path[n] == 'S') {
                y = y - 1;
            } else if (path[n] == 'E') {
                x = x + 1;
            }else if (path[n] == 'W') {
                x = x - 1;
            }
            step_type simple_step(x, y);
            vector<step_type>::iterator result = find(step.begin( ), step.end( ), simple_step); //查找3
            if (result == step.end()){
                step.push_back(simple_step);
            } else {
                return true;
            }
        }
        return false;
    }
};