牛客 在其他数都出现k次的数组中找到出现1次的数

题目链接：https://www.nowcoder.com/practice/26e46f1f5e0d48c4b9ba13fe3e8d0ec6?tpId=101&tqId=33216&tPage=1&rp=1&ru=/ta/programmer-code-interview-guide&qru=/ta/programmer-code-interview-guide/question-ranking

题目大意：

　　略。

分析：

　　k进制异或.

代码如下：

 #include <bits/stdc++.h>
 using namespace std;

 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
 #define Rep(i,n) for (int i = 0; i < (int)(n); ++i)
 #define For(i,s,t) for (int i = (int)(s); i <= (int)(t); ++i)
 #define rFor(i,t,s) for (int i = (int)(t); i >= (int)(s); --i)
 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)

 #define pr(x) cout << #x << " = " << x << "  "
 #define prln(x) cout << #x << " = " << x << endl

 #define LOWBIT(x) ((x)&(-x))

 #define ALL(x) x.begin(),x.end()
 #define INS(x) inserter(x,x.begin())
 #define UNIQUE(x) x.erase(unique(x.begin(), x.end()), x.end())
 #define REMOVE(x, c) x.erase(remove(x.begin(), x.end(), c), x.end()); // 删去 x 中所有 c
 #define TOLOWER(x) transform(x.begin(), x.end(), x.begin(),::tolower);
 #define TOUPPER(x) transform(x.begin(), x.end(), x.begin(),::toupper);

 #define ms0(a) memset(a,0,sizeof(a))
 #define msI(a) memset(a,0x3f,sizeof(a))
 #define msM(a) memset(a,-1,sizeof(a))

 #define MP make_pair
 #define PB push_back
 #define ft first
 #define sd second

 template<typename T1, typename T2>
 istream &operator>>(istream &in, pair<T1, T2> &p) {
     in >> p.first >> p.second;
     return in;
 }

 template<typename T>
 istream &operator>>(istream &in, vector<T> &v) {
     for (auto &x: v)
         in >> x;
     return in;
 }

 template<typename T>
 ostream &operator<<(ostream &out, vector<T> &v) {
     Rep(i, v.size()) out << v[i] << " \n"[i == v.size() - ];
     return out;
 }

 template<typename T1, typename T2>
 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
     out << "[" << p.first << ", " << p.second << "]" << "\n";
     return out;
 }

 inline int gc(){
     static const int BUF = 1e7;
     static char buf[BUF], *bg = buf + BUF, *ed = bg;

     if(bg == ed) fread(bg = buf, , BUF, stdin);
     return *bg++;
 } 

 inline int ri(){
     int x = , f = , c = gc();
     for(; c<||c>; f = c=='-'?-:f, c=gc());
     for(; c>&&c<; x = x* + c - , c=gc());
     return x*f;
 }

 template<class T>
 inline string toString(T x) {
     ostringstream sout;
     sout << x;
     return sout.str();
 }

 inline int toInt(string s) {
     int v;
     istringstream sin(s);
     sin >> v;
     return v;
 }

 //min <= aim <= max
 template<typename T>
 inline bool BETWEEN(const T aim, const T min, const T max) {
     return min <= aim && aim <= max;
 }

 typedef unsigned int uI;
 typedef long long LL;
 typedef unsigned long long uLL;
 typedef vector< int > VI;
 typedef vector< bool > VB;
 typedef vector< char > VC;
 typedef vector< double > VD;
 typedef vector< string > VS;
 typedef vector< LL > VL;
 typedef vector< VI > VVI;
 typedef vector< VB > VVB;
 typedef vector< VS > VVS;
 typedef vector< VL > VVL;
 typedef vector< VVI > VVVI;
 typedef vector< VVL > VVVL;
 typedef pair< int, int > PII;
 typedef pair< LL, LL > PLL;
 typedef pair< int, string > PIS;
 typedef pair< string, int > PSI;
 typedef pair< string, string > PSS;
 typedef pair< double, double > PDD;
 typedef vector< PII > VPII;
 typedef vector< PLL > VPLL;
 typedef vector< VPII > VVPII;
 typedef vector< VPLL > VVPLL;
 typedef vector< VS > VVS;
 typedef map< int, int > MII;
 typedef unordered_map< int, int > uMII;
 typedef map< LL, LL > MLL;
 typedef map< string, int > MSI;
 typedef map< int, string > MIS;
 typedef multiset< int > mSI;
 typedef multiset< char > mSC;
 typedef set< int > SI;
 typedef stack< int > SKI;
 typedef stack< char > SKC;
 typedef deque< int > DQI;
 typedef queue< int > QI;
 typedef priority_queue< int > PQIMax;
 typedef priority_queue< int, VI, greater< int > > PQIMin;
 const double EPS = 1e-;
 const LL inf = 0x7fffffff;
 const LL infLL = 0x7fffffffffffffffLL;
 const LL mod = 1e9 + ;
 const int maxN = 1e5 + ;
 const LL ONE = ;
 const LL evenBits = 0xaaaaaaaaaaaaaaaa;
 const LL oddBits = 0x5555555555555555;

 int N, k, nums[maxN]; 

 // k 进制异或和
 int singleNumber() {
     int res = ;
     Rep(i, ) {
         int sum = ;
         Rep(j, N) {
             // 取nums[j]的第i位值，然后加起来
             sum += (nums[j] >> i) & ;
         }
         // sum目前的有进位相加的结果，模k以后就是无进位相加的结果
         res |= (sum % k) << i;
     }
     return res;
 }

 int main() {
     //freopen("MyOutput.txt","w",stdout);
     //freopen("input.txt","r",stdin);
     //INIT();
     scanf("%d%d", &N, &k);
     Rep(i, N) scanf("%d", &nums[i]);
     printf("%d", singleNumber());
     return ;
 }