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Instead of moving from the startValue
to target
, consider reversing the operations. Start from the target
and attempt to reach the startValue
. If the target
is even, divide it by 2. If it is odd, add 1 to it. Continue until the target
is less than or equal to the startValue
. This allows you to efficiently compute the minimum steps by potentially making large reductions through division by 2.
Time Complexity: O(log n)
, where n
is the target due to halving operation.
Space Complexity: O(1)
as no extra space is used.
1#include <stdio.h>
2
3int brokenCalc(int startValue, int target) {
4 int operations = 0;
5 while (target > startValue) {
6 operations++;
7 if (target % 2 == 1) {
8 target++;
9 } else {
10 target /= 2;
11 }
12 }
13 return operations + (startValue - target);
14}
15
16int main() {
17 int startValue = 3, target = 10;
18 printf("%d\n", brokenCalc(startValue, target));
19 return 0;
20}
This C program uses a loop to apply reverse operations to reduce the target to a value no larger than the startValue. If target is even, it is divided by 2; if odd, it is incremented by 1. Lastly, the remaining difference between startValue and target is added to the operations, as this represents the needed decrements.
Using a greedy approach, always attempt the operation that brings the target closer to the startValue significantly, which is multiplication by 2 in the reverse. Only when all doubling possibilities are exhausted, should we use subtraction/addition operations.
Time Complexity: O(log n)
due to division operations.
Space Complexity: O(1)
.
1function
This JavaScript code applies a choice strategy, maximizing the utility of division while fulfilling the role of additions when necessary, to achieve accurate operation counts.