**Sum of Three Numbers Less than Target - Google Top Interview Questions**

### Problem Statement :

Given a list of integers nums and an integer target, return the number of triples i < j < k that exist such that nums[i] + nums[j] + nums[k] < target. Constraints n ≤ 1,000 where n is the length of nums Example 1 Input nums = [-3, 5, 3, 2, 7] target = 9 Output 5 Explanation Here are the different triples' values: -3 + 5 + 3 = 5 -3 + 5 + 2 = 4 -3 + 3 + 2 = 2 -3 + 3 + 7 = 7 -3 + 2 + 7 = 6

### Solution :

` ````
Solution in C++ :
int solve(vector<int>& nums, int target) {
sort(nums.begin(), nums.end());
int ans = 0;
for (int i = 0; i < nums.size(); i++) {
for (int j = i + 1, k = nums.size() - 1; j < k;) {
if (nums[i] + nums[j] + nums[k] < target) {
ans += k - j;
j++;
} else {
k--;
}
}
}
return ans;
}
```

` ````
Solution in Java :
import java.util.*;
class Solution {
public int solve(int[] nums, int target) {
int res = 0;
Arrays.sort(nums);
for (int i = 0; i < nums.length; i++) res += twoSum(nums, target, i);
return res;
}
// Two pointer function to find all triplets less than target
public int twoSum(int[] nums, int target, int i) {
int j = i + 1, k = nums.length - 1, res = 0;
// Do not do i <= j because the same index cannot be used twice
while (j < k) {
int total = nums[i] + nums[j] + nums[k];
if (total >= target)
k--;
// The array is sorted so all triplets using a smaller k can be added
else {
res += k - j;
j++;
}
}
return res;
}
}
```

` ````
Solution in Python :
class Solution:
def two_sum(self, nums, start, val, target):
a, b = start, len(nums) - 1
ans = 0
while a < b:
if nums[a] + nums[b] + val < target:
a += 1
ans += b - a + 1
else:
b -= 1
return ans
def solve(self, nums, target):
nums.sort()
return sum(self.two_sum(nums, i + 1, nums[i], target) for i in range(len(nums)))
```

## View More Similar Problems

## Components in a graph

There are 2 * N nodes in an undirected graph, and a number of edges connecting some nodes. In each edge, the first value will be between 1 and N, inclusive. The second node will be between N + 1 and , 2 * N inclusive. Given a list of edges, determine the size of the smallest and largest connected components that have or more nodes. A node can have any number of connections. The highest node valu

View Solution →## Kundu and Tree

Kundu is true tree lover. Tree is a connected graph having N vertices and N-1 edges. Today when he got a tree, he colored each edge with one of either red(r) or black(b) color. He is interested in knowing how many triplets(a,b,c) of vertices are there , such that, there is atleast one edge having red color on all the three paths i.e. from vertex a to b, vertex b to c and vertex c to a . Note that

View Solution →## Super Maximum Cost Queries

Victoria has a tree, T , consisting of N nodes numbered from 1 to N. Each edge from node Ui to Vi in tree T has an integer weight, Wi. Let's define the cost, C, of a path from some node X to some other node Y as the maximum weight ( W ) for any edge in the unique path from node X to Y node . Victoria wants your help processing Q queries on tree T, where each query contains 2 integers, L and

View Solution →## Contacts

We're going to make our own Contacts application! The application must perform two types of operations: 1 . add name, where name is a string denoting a contact name. This must store name as a new contact in the application. find partial, where partial is a string denoting a partial name to search the application for. It must count the number of contacts starting partial with and print the co

View Solution →## No Prefix Set

There is a given list of strings where each string contains only lowercase letters from a - j, inclusive. The set of strings is said to be a GOOD SET if no string is a prefix of another string. In this case, print GOOD SET. Otherwise, print BAD SET on the first line followed by the string being checked. Note If two strings are identical, they are prefixes of each other. Function Descriptio

View Solution →## Cube Summation

You are given a 3-D Matrix in which each block contains 0 initially. The first block is defined by the coordinate (1,1,1) and the last block is defined by the coordinate (N,N,N). There are two types of queries. UPDATE x y z W updates the value of block (x,y,z) to W. QUERY x1 y1 z1 x2 y2 z2 calculates the sum of the value of blocks whose x coordinate is between x1 and x2 (inclusive), y coor

View Solution →