You have a bomb to defuse, and your time is running out! Your informer will provide you with a circular array code of length of n and a key k.
To decrypt the code, you must replace every number. All the numbers are replaced simultaneously.
If k > 0, replace the ith number with the sum of the next k numbers.
If k < 0, replace the ith number with the sum of the previous k numbers.
If k == 0, replace the ith number with 0.As code is circular, the next element of code[n-1] is code[0], and the previous element of code[0] is code[n-1].
Given the circular array code and an integer key k, return the decrypted code to defuse the bomb!
Example 1:
Input: code = [5,7,1,4], k = 3
Output: [12,10,16,13]
Explanation: Each number is replaced by the sum of the next 3 numbers. The decrypted code is [7+1+4, 1+4+5, 4+5+7, 5+7+1]. Notice that the numbers wrap around.
Flow Diagram: –
Solution: –
class Solution {
public int[] decrypt(int[] code, int k) {
int[] res = new int[code.length];
if (k == 0) return res;
//Define the initial window and initial sum
int start = 1, end = k, sum = 0;
if (k < 0) {//If k < 0, the starting point will be end of the array.
k = -k;
start = code.length - k;
end = code.length - 1;
}
for (int i = start; i <= end; i++) sum += code[i];
//Scan through the code array as i moving to the right, update the window sum.
for (int i = 0; i < code.length; i++) {
res[i] = sum;
sum -= code[(start++) % code.length];
sum += code[(++end) % code.length];
}
return res;
}
}