alg_00.cc

// Copyright [2015] <Yu Jing>
#include <cstdio>

#include <string>
#include <map>

using std::string;
using std::map;

char ch_searcher(const std::string & s) {
    map<char, bool> labels;
    for (unsigned i = 0; i < s.length(); i++) {
        if (labels.find(s[i]) != labels.end()) {
            labels[s[i]] = false;
        } else {
            labels.insert(std::make_pair(s[i], true));
        }
    }
    for (unsigned i = 0; i < s.length(); i++) {
        if (labels[s[i]]) return s[i];
    }
    return -1;
}


int main(int argc, char * argv[]) {
    const char * dstr = "abcab";
    if (argc > 1) {
        printf("%c - %d \n", ch_searcher(argv[1]), ch_searcher(argv[1]));
    } else {
        printf("%c - %d \n", ch_searcher(dstr), ch_searcher(dstr));
    }
    return 0;
}