A non-empty array A consisting of N integers is given. A pair of integers (P, Q), such that 0 ≤ P < Q < N, is called a slice of array A (notice that the slice contains at least two elements). The average of a slice (P, Q) is the sum of A[P] + A[P + 1] + ... + A[Q] divided by the length of the slice. To be precise, the average equals (A[P] + A[P + 1] + ... + A[Q]) / (Q − P + 1).
For example, array A such that:
A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8contains the following example slices:
- slice (1, 2), whose average is (2 + 2) / 2 = 2;
- slice (3, 4), whose average is (5 + 1) / 2 = 3;
- slice (1, 4), whose average is (2 + 2 + 5 + 1) / 4 = 2.5.
The goal is to find the starting position of a slice whose average is minimal.
Write a function:
int solution(vector<int> &A);
that, given a non-empty array A consisting of N integers, returns the starting position of the slice with the minimal average. If there is more than one slice with a minimal average, you should return the smallest starting position of such a slice.
For example, given array A such that:
A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8the function should return 1, as explained above.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [2..100,000];
- each element of array A is an integer within the range [−10,000..10,000].
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int min_index = 0;
double min = (A[0] + A[1]) / 2;
for(unsigned int i = 2; i < A.size(); i++){
double temp_three = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
double temp_two = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
for(unsigned int i = 2; i < A.size(); i++){
double temp_three = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
double temp_two = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double temp_three = 0,
for(unsigned int i = 2; i < A.size(); i++){
double temp_three = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
double temp_two = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
double temp_three = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
double temp_two = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
min_index = i - 2;
}
if(temp_two < min){
min = temp_two;
min_index = i - 1;
}
}
return min_index;
}
func.cpp: In function 'int solution(std::vector<int>&)': func.cpp:14:12: error: 'temp_three' was not declared in this scope if(temp_three < min){ ^~~~~~~~~~ func.cpp:16:11: error: 'min_index' was not declared in this scope min_index = i - 2; ^~~~~~~~~ func.cpp:18:12: error: 'temp_two' was not declared in this scope if(temp_two < min){ ^~~~~~~~ func.cpp:20:13: error: 'min_index' was not declared in this scope min_index = i - 1; ^~~~~~~~~ func.cpp:24:12: error: 'min_index' was not declared in this scope return min_index; ^~~~~~~~~ func.cpp:4:9: warning: unused variable 'index' [-Wunused-variable] int index = 0; ^~~~~
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(temp_three < min){
min = temp_three;
index = i - 2;
}
if(temp_two < min){
min = temp_two;
index = i - 1;
}
}
return index;
}
func.cpp: In function 'int solution(std::vector<int>&)': func.cpp:14:12: error: 'temp_three' was not declared in this scope if(temp_three < min){ ^~~~~~~~~~ func.cpp:18:12: error: 'temp_two' was not declared in this scope if(temp_two < min){ ^~~~~~~~
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(three_avg < min){
min = temp_three;
index = i - 2;
}
if(temp_two < min){
min = temp_two;
index = i - 1;
}
}
return index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(two_avg < min){
min = temp_two;
index = i - 1;
}
if(three_avg < min){
min = temp_three;
index = i - 2;
}
}
return index;
}
func.cpp: In function 'int solution(std::vector<int>&)': func.cpp:15:19: error: 'temp_two' was not declared in this scope min = temp_two; ^~~~~~~~ func.cpp:19:17: error: 'temp_three' was not declared in this scope min = temp_three; ^~~~~~~~~~
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(two_avg < min){
min = two_avg;
index = i - 1;
}
if(three_avg < min){
min = three_avg;
index = i - 2;
}
}
return index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(two_avg < min){
min = two_avg;
index = i - 1;
}
if(three_avg < min){
min = three_avg;
index = i - 2;
}
}
return index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(two_avg < min){
min = two_avg;
index = i - 1;
}
if(three_avg < min){
min = three_avg;
index = i - 2;
}
}
return index;
}
int solution(vector<int> &A) {
// write your code in C++14 (g++ 6.2.0)
if(A.size() < 2) return 0;
int index = 0;
double min = (A[0] + A[1]) / 2;
double two_avg = 0, three_avg = 0;
for(unsigned int i = 2; i < A.size(); i++){
three_avg = (A[i - 2] + A[ i - 1] + A[i]) / 3.0;
two_avg = (A[ i - 1] + A[i]) / 2.0;
if(two_avg < min){
min = two_avg;
index = i - 1;
}
if(three_avg < min){
min = three_avg;
index = i - 2;
}
}
return index;
}
The solution obtained perfect score.