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_724.java
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_724.java
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package com.fishercoder.solutions;
public class _724 {
public static class Solution1 {
/**
* Space: O(n)
* Time: O(n)
*/
public int pivotIndex(int[] nums) {
if (nums == null || nums.length == 0) {
return -1;
}
int[] sums = new int[nums.length];
sums[0] = nums[0];
for (int i = 1; i < nums.length; i++) {
sums[i] = sums[i - 1] + nums[i];
}
for (int i = 0; i < nums.length; i++) {
if (i == 0 && 0 == sums[nums.length - 1] - sums[i] || (i > 0 && sums[i - 1] == sums[nums.length - 1] - sums[i])) {
return i;
}
}
return -1;
}
}
public static class Solution2 {
/**
* Space: O(1)
* Time: O(n)
*/
public int pivotIndex(int[] nums) {
int total = 0;
for (int num : nums) {
total += num;
}
int sum = 0;
for (int i = 0; i < nums.length; sum += nums[i++]) {
if (sum * 2 == total - nums[i]) {
return i;
}
}
return -1;
}
}
}