5ms 98.8% Java Solution


  • 4
    O
    public class Solution {
        public void xwap(int[] a, int i, int j) { 
            int tmp=a[i]; 
            a[i]=a[j]; 
            a[j]=tmp; 
        } 
         
        public void qsort(int[] a, int[] indice, int s, int t) { 
            if (s>=t) return; 
            int mid=a[(s+t)/2], i=s, j=t; 
            while (i<j) { 
                while (i<j && a[i]<mid) i++; 
                while (i<j && a[j]>mid) j--; 
                if (a[i]==mid && a[j]==mid) j--; 
                if (i<j) { 
                    xwap(a,i,j); 
                    xwap(indice,i,j); 
                } 
            } 
            qsort(a,indice,s,i-1); 
            qsort(a,indice,i+1,t); 
        } 
    
        public boolean containsNearbyDuplicate(int[] nums, int k) { 
            if (nums==null) return false; 
            if (nums.length<2) return false; 
            int n=nums.length; 
            int[] indice = new int[n]; 
            for (int i=0; i<n; i++) indice[i]=i; 
            qsort(nums,indice,0,n-1); 
    
            for (int i=0; i<n; i++) {
                int j=i+1;
                while (j<n && nums[j]==nums[i]) {
                    if (Math.abs(indice[i]-indice[j])<=k) return true;
                    j++;
                }
            }
                
            return false; 
        }
    }

  • 0
    N

    Hi, I appreciate the mapping way designed by yourself. But quicksort here could be easily degrade? I checked the testcase by increasing order. Did you avoid this by choosing pivot as middle one?


  • 0
    O

    I didn't aovid it. A carefully designed test cases can degrade qsort efficiency. I didn't consider those cases. But in general qsort is sufficient.


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