added Minimum Value to Get Positive Step by Step Sum (easy)

Author: minhyeong-joe

Easy/MinValStepSum/README.md

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+
+# Minimum Value to Get Positive Step by Step Sum
+[Leetcode Link](https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum/)
+
+## Problem:
+
+Given an array of integers `nums`, you start with an initial **positive** value *startValue*.
+
+In each iteration, you calculate the step by step sum of *startValue* plus elements in `nums` (from left to right).
+
+Return the minimum **positive** value of *startValue* such that the step by step sum is never less than 1.
+
+ 
+
+## Example:
+
+```
+Input: nums = [-3,2,-3,4,2]
+Output: 5
+Explanation: If you choose startValue = 4, in the third iteration your step by step sum is less than 1.
+ step by step sum
+ startValue = 4 | startValue = 5 | nums
+ (4 -3 ) = 1 | (5 -3 ) = 2 | -3
+ (1 +2 ) = 3 | (2 +2 ) = 4 | 2
+ (3 -3 ) = 0 | (4 -3 ) = 1 | -3
+ (0 +4 ) = 4 | (1 +4 ) = 5 | 4
+ (4 +2 ) = 6 | (5 +2 ) = 7 | 2
+```
+```
+Input: nums = [1,2]
+Output: 1
+Explanation: Minimum start value should be positive. 
+```
+```
+Input: nums = [1,-2,-3]
+Output: 5
+```
+
+## Note:
+
+- `1 <= nums.length <= 100`
+- `-100 <= nums[i] <= 100`

Easy/MinValStepSum/Solution.java

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+// Let positive start value be X
+// For each num in nums:
+// the step sum value is X + num[0], X + num[0] + num[1]...
+// so for each num, the sum value is X + SUM(num so far)
+// we just need to guarantee that sum value is positive for any SUM(num so far)
+
+package Easy.MinValStepSum;
+
+/**
+ * Solution
+ */
+public class Solution {
+
+ public int minStartValue(int[] nums) {
+ int startVal = 1;
+ int sum = 0;
+ for (int num : nums) {
+ sum += num;
+ if (startVal + sum < 1) {
+ startVal = 1 - sum;
+ }
+ }
+ return startVal;
+ }
+
+}

Easy/MinValStepSum/TestDriver.java

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+package Easy.MinValStepSum;
+
+import java.util.Arrays;
+
+public class TestDriver {
+ 
+ public static void main(String[] args) {
+ Solution sol = new Solution();
+ int nums1[] = {-3, 2, -3, 4, 2};
+ System.out.println("Input: nums = " + Arrays.toString(nums1));
+ System.out.println("Output: " + sol.minStartValue(nums1));
+ System.out.println();
+
+ int nums2[] = {1, 2};
+ System.out.println("Input: nums = " + Arrays.toString(nums2));
+ System.out.println("Output: " + sol.minStartValue(nums2));
+ System.out.println();
+
+ int nums3[] = {1, -2, -3};
+ System.out.println("Input: nums = " + Arrays.toString(nums3));
+ System.out.println("Output: " + sol.minStartValue(nums3));
+ System.out.println();
+ }
+
+}

README.md

@@ -21,6 +21,7 @@ Languages used: Java and Python
  - [Find Common Characters](Easy/FindCommonCharacters)
  - [Third Maximum Number](Easy/ThirdMaximumNumber)
  - [String Matching in an Array](Easy/StringMatchingInArray)
+ - [Minimum Value to Get Positive Step by Step Sum](Easy/MinValStepSum)
 - Medium
  - [Minimum Add to Make Parentheses Valid](Medium/MinimumAddtoMakeParenthesesValid)
  - [Distribute Coins in Binary Tree](Medium/DistributionCoinsInBinaryTree)