HDU - 5178 - pairs

pairs

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 349 Accepted Submission(s): 151


Problem Description John has n points on the X axis, and their coordinates are (x[i],0),(i=0,1,2,…,n?1). He wants to know how many pairs that |x[b]?x[a]|≤k.(a
Input The first line contains a single integer T (about 5), indicating the number of cases.
Each test case begins with two integers n,k(1≤n≤100000,1≤k≤109).
Next n lines contain an integer x[i](?109≤x[i]≤109), means the X coordinates.
Output For each case, output an integer means how many pairs that |x[b]?x[a]|≤k.
Sample Input

2
5 5
-100
0
100
101
102
5 300
-100
0
100
101
102

Sample Output

3
10

Source BestCoder Round #31

寫傻逼了，居然還超時了。。

AC代碼：

#include 
#include 
#include 
#include 
#include 
#define LL long long
using namespace std;

int a[100005];

int main() {
    int T;
    scanf("%d", &T);
    while(T--) {
        int n, k;
        scanf("%d %d", &n, &k);
        
        for(int i = 0; i < n; i++) {
            scanf("%d", &a[i]);
        }
        sort(a, a+n);
        
        LL ans = 0;
        for(int i = 0, j = 0; i < n; i++) {
        	while(j + 1 < n && a[j + 1] - a[i] <= k) j++;
        	ans += (j - i);
        }
        
        cout << ans << endl;
    }
    return 0;
}