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| 1 | +class Solution { |
| 2 | + public int numSubseq(int[] nums, int target) { |
| 3 | + Arrays.sort(nums); |
| 4 | + int mod = 1_000_000_007; |
| 5 | + int result =0; |
| 6 | + int n = nums.length; |
| 7 | + int[] power = new int[n]; |
| 8 | + power[0] = 1; |
| 9 | + for(int i=1;i<n;i++){ |
| 10 | + power[i] = (power[i-1] * 2) % mod; |
| 11 | + } |
| 12 | + |
| 13 | + for(int left=0;left<n;left++){ |
| 14 | + int right = binarySearch(nums,target- nums[left]) - 1; |
| 15 | + if(right>=left){ |
| 16 | + result += power[right - left]; |
| 17 | + result %= mod; |
| 18 | + } |
| 19 | + } |
| 20 | + |
| 21 | + return result; |
| 22 | + } |
| 23 | + |
| 24 | + private int binarySearch(int[] nums, int value){ |
| 25 | + int low = 0, high = nums.length - 1; |
| 26 | + while(low<=high){ |
| 27 | + int mid = low + (high - low)/2; |
| 28 | + if(nums[mid]<=value){ |
| 29 | + low = mid + 1; |
| 30 | + } |
| 31 | + else{ |
| 32 | + high = mid - 1; |
| 33 | + } |
| 34 | + } |
| 35 | + return low; |
| 36 | + } |
| 37 | +} |
| 38 | + |
| 39 | +class Solution { |
| 40 | + public int numSubseq(int[] nums, int target) { |
| 41 | + Arrays.sort(nums); |
| 42 | + int mod = 1_000_000_007; |
| 43 | + int result =0; |
| 44 | + int n = nums.length; |
| 45 | + int[] power = new int[n]; |
| 46 | + power[0] = 1; |
| 47 | + for(int i=1;i<n;i++){ |
| 48 | + power[i] = (power[i-1] * 2) % mod; |
| 49 | + } |
| 50 | + int left = 0 , right = n - 1; |
| 51 | + |
| 52 | + while(left<=right){ |
| 53 | + if(nums[left] + nums[right] <= target){ |
| 54 | + result += power[right - left]; |
| 55 | + result %= mod; |
| 56 | + left++; |
| 57 | + } |
| 58 | + else{ |
| 59 | + right--; |
| 60 | + } |
| 61 | + } |
| 62 | + |
| 63 | + return result; |
| 64 | + } |
| 65 | +} |
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