/**
*
* 1.平衡点问题 平衡点：比如int[] numbers = {1,3,5,7,8,25,4,20};
* 25前面的总和为24，25后面的总和也是24，25这个点就是平衡点；假如一个数组中的元素，其前面的部分等于后面的部分，那么这个点的位序就是平衡点
* 要求：返回任何一个平衡点
*
* @author fangtengfei
* @date 2010-5-15
*/
public class BalancePoint {
public static void main(String[] args) {
// 有平衡点，且平衡点是个数据
int[] hasBalancePointValueNumbers = { 1, 2, 3, 4, 5, 6, 7, 8 };
// 有平衡点，且平衡点是索引
int[] hasBalancePointIndexNumbers = { 1, 3, 5, 7, 8, 4, 20 };
// 无平衡点
int[] noBalancePointNumbers = { 1, 3, 5, 7, 8, 4, 20, 12, 13 };
}
private static int queryBalancePoint(int[] noBalancePointNumbers) {
int frontIndex = 0, backIndex = noBalancePointNumbers.length - 1;
int temp = 0;
// 判断前后索引不相等，那临时数减去前面的大于零则++，小于0则--
while (frontIndex != backIndex) {
if (temp - noBalancePointNumbers[frontIndex] >= 0) {
temp -= noBalancePointNumbers[frontIndex];
frontIndex++;
} else {
temp += noBalancePointNumbers[backIndex];
backIndex--;
}
}
// 当索引一样时，临时数等于0则返回当前数，<>0则返回当前索引。
if (backIndex - frontIndex == 0) {
if (temp == 0) {
return noBalancePointNumbers[frontIndex];
}
if (temp - noBalancePointNumbers[frontIndex] == 0) {
return frontIndex;
}
}
return -1;
}
}
