Two Sum II – Input Array Is Sorted – LeetCode Solution Java , Python 3, Python 2 , C , C++, Best and Optimal Solutions , All you need.

Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.

Return the indices of the two numbers, index1 and index2, added by one as an integer array [index1, index2] of length 2.

The tests are generated such that there is exactly one solution. You may not use the same element twice.

Your solution must use only constant extra space.

Example 1:

Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].

Example 2:

Input: numbers = [2,3,4], target = 6
Output: [1,3]
Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3].

Example 3:

Input: numbers = [-1,0], target = -1
Output: [1,2]
Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1, index2 = 2. We return [1, 2].

Constraints:

• 2 <= numbers.length <= 3 * 104
• -1000 <= numbers[i] <= 1000
• numbers is sorted in non-decreasing order.
• -1000 <= target <= 1000
• The tests are generated such that there is exactly one solution.

C++ Two Sum II – Input Array Is Sorted  LeetCode Solution

 vector<int> twoSum(vector<int>& numbers, int target) {
    
    int l = 0;
    int r = numbers.size() -1;
   
    while(l < r){
        if(numbers[l] + numbers[r] == target){
           
            return {l+1,r+1};;
        }
        else if(numbers[l] + numbers[r] > target){
            r--;
        }
        else{
            l++;
        }
    }
	return {};
}

Java Two Sum II – Input Array Is SortedLeetCode Solution

public int[] twoSum(int[] num, int target) {
    int[] indice = new int[2];
    if (num == null || num.length < 2) return indice;
    int left = 0, right = num.length - 1;
    while (left < right) {
        int v = num[left] + num[right];
        if (v == target) {
            indice[0] = left + 1;
            indice[1] = right + 1;
            break;
        } else if (v > target) {
            right --;
        } else {
            left ++;
        }
    }
    return indice;
}
 

Python 3 Two Sum II – Input Array Is Sorted LeetCode Solution

# two-pointer
def twoSum1(self, numbers, target):
    l, r = 0, len(numbers)-1
    while l < r:
        s = numbers[l] + numbers[r]
        if s == target:
            return [l+1, r+1]
        elif s < target:
            l += 1
        else:
            r -= 1
 
# dictionary           
def twoSum2(self, numbers, target):
    dic = {}
    for i, num in enumerate(numbers):
        if target-num in dic:
            return [dic[target-num]+1, i+1]
        dic[num] = i
 
# binary search        
def twoSum(self, numbers, target):
    for i in xrange(len(numbers)):
        l, r = i+1, len(numbers)-1
        tmp = target - numbers[i]
        while l <= r:
            mid = l + (r-l)//2
            if numbers[mid] == tmp:
                return [i+1, mid+1]
            elif numbers[mid] < tmp:
                l = mid+1
            else:
                r = mid-1

Array-1180
String-562
Hash Table-412
Dynamic Programming-390
Math-368
Sorting-264
Greedy-257
Depth-First Search-256
Database-215
Breadth-First Search-200
Tree-195
Binary Search-191
Matrix-176
Binary Tree-160
Two Pointers-151
Bit Manipulation-140
Stack-133
Heap (Priority Queue)-117
Design-116
Graph-108
Simulation-103
Prefix Sum-96
Backtracking-92
Counting-86
Sliding Window-73
Linked List-69
Union Find-66
Ordered Set-48
Monotonic Stack-47
Recursion-43
Trie-41
Binary Search Tree-40
Divide and Conquer-40
Enumeration-39
Bitmask-37
Queue-33
Memoization-32
Topological Sort-31
Geometry-30
Segment Tree-27
Game Theory-24
Hash Function-24
Binary Indexed Tree-21
Interactive-18
Data Stream-17
String Matching-17
Rolling Hash-17
Shortest Path-16
Number Theory-16
Combinatorics-15
Randomized-12
Monotonic Queue-9
Iterator-9
Merge Sort-9
Concurrency-9
Doubly-Linked List-8
Brainteaser-8
Probability and Statistics-7
Quickselect-7
Bucket Sort-6
Suffix Array-6
Minimum Spanning Tree-5
Counting Sort-5
Shell-4
Line Sweep-4
Reservoir Sampling-4
Eulerian Circuit-3
Radix Sort-3
Strongly Connected Componen-t2
Rejection Sampling-2
Biconnected Component-1

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