41 lines
1.1 KiB
C++
41 lines
1.1 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 200010;
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int a[N];
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int c;
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typedef long long LL;
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LL cnt;
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int main() {
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int n;
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cin >> n >> c;
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for (int i = 1; i <= n; i++) cin >> a[i];
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sort(a + 1, a + 1 + n);
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//遍历每一个数字
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for (int i = 1; i < n; i++) {
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int left = 0, right = 0;
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//左端点
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int l = 1, r = n, k = a[i] + c;
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while (l < r) {
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int mid = (l + r) >> 1;
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if (a[mid] >= k)r = mid;
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else l = mid + 1;
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}
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//也行找的到，也许找不到~
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if (a[l] == k)left = l;
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//右端点
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l = 1, r = n;
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while (l < r) {
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int mid = (l + r + 1) >> 1;
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if (a[mid] <= k)l = mid;
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else r = mid - 1;
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}
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//如果left存在，那么right也一定存在，大不了left=right嘛
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if (left) right = l;
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//左右端点差就是个数
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if (left) cnt += right - left + 1;//right==left,那就是1个
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}
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printf("%lld", cnt);
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return 0;
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} |