Submission #67961

#	Time	Username	Problem	Language	Result	Execution time	Memory
67961		ekrem	XOR Sum (info1cup17_xorsum)	C++98	77 / 100	1644 ms	19564 KiB

xorsum

#include <bits/stdc++.h>
#define st first
#define nd second
#define mp make_pair
#define pb push_back
#define N 1000005
using namespace std;

typedef pair < int , int > ii;
typedef vector < int > vi;

int n, ans, a[N];
pair < int , int > b[N], c[N];

int main() {
	// freopen("in.txt", "r", stdin);
	// freopen("out.txt", "w", stdout);
	scanf("%d",&n);
	for(int i = 1; i <= n; i++){
		scanf("%d",a + i);
		b[i] = mp(a[i]%2, i);
	}
	sort(b + 1, b + n + 1);
	for(int k = 0; k <= 28; k++){
		int x = n + 1, y = n + 1, z = n + 1, say = 0;
		for(int i = 1; i <= n; i++){
			while(x >= 2 and b[x - 1].st >= (1<<k) - b[i].st)x--;
			while(y >= 2 and b[y - 1].st >= (1<<(k+1) ) - b[i].st)y--;
			while(z >= 2 and b[z - 1].st >= (1<<k) + (1<<(k+1)) - b[i].st)z--;
			say += max(y, i) - max(x, i);
			say += n - max(z, i) + 1;
			say = say%2;
			// printf("%d %d %d\n",x ,y ,z);
		}
		// cout << "\nAMK\n";
		int ind = 0, xx = 0;
		for(int i = 1; i <= n; i++){
			if(a[b[i].nd ]&(1<<(k + 1)))
				c[++xx] = (mp(b[i].st + (a[b[i].nd ]&(1<<(k + 1))) , b[i].nd));
			else
				b[++ind] = b[i];
			// b[i].st += a[b[i].nd ]&(1<<(k + 1));
		}
		for(int i = 1; i <= xx; i++)
			b[++ind] = c[i];
		ans += (1<<k)*(say%2);
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:18:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
xorsum.cpp:20:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",a + i);
   ~~~~~^~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 38 / 38
• Subtask 5: 0 / 23