2020牛客寒假算法基础集训营4-D子段异或

 

思路

　　

 CODE

 1 #include <bits/stdc++.h>
 2 #define dbg(x) cout << #x << "=" << x << endl
 3 
 4 using namespace std;
 5 typedef long long LL;
 6 
 7 template<class T>inline void read(T &res)
 8 {
 9     char c;T flag=1;
10     while((c=getchar())<'0'||c>'9')if(c=='-')flag=-1;res=c-'0';
11     while((c=getchar())>='0'&&c<='9')res=res*10+c-'0';res*=flag;
12 }
13 
14 namespace _buff {
15     const size_t BUFF = 1 << 19;
16     char ibuf[BUFF], *ib = ibuf, *ie = ibuf;
17     char getc() {
18         if (ib == ie) {
19             ib = ibuf;
20             ie = ibuf + fread(ibuf, 1, BUFF, stdin);
21         }
22         return ib == ie ? -1 : *ib++;
23     }
24 }
25 
26 int qread() {
27     using namespace _buff;
28     int ret = 0;
29     bool pos = true;
30     char c = getc();
31     for (; (c < '0' || c > '9') && c != '-'; c = getc()) {
32         assert(~c);
33     }
34     if (c == '-') {
35         pos = false;
36         c = getc();
37     }
38     for (; c >= '0' && c <= '9'; c = getc()) {
39         ret = (ret << 3) + (ret << 1) + (c ^ 48);
40     }
41     return pos ? ret : -ret;
42 }
43 
44 const int maxn = 2e5 + 7;
45 
46 map <int, int> mapp;
47 int a[maxn];
48 int n;
49 int xorsum[maxn];
50 
51 int main()
52 {
53     read(n);
54     for(int i = 1; i <= n; ++i) {
55         read(a[i]);
56         xorsum[i] = xorsum[i-1];
57         xorsum[i] ^= a[i];
58     }
59     mapp[0] = 1;
60     LL ans = 0;
61 
62     for(int i = 1; i <= n; ++i) {
63         if(mapp[xorsum[i]]) {
64             ans += mapp[xorsum[i]];
65         }
66         mapp[xorsum[i]]++;
67     }
68     cout << ans << endl;
69     return 0;
70 }

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