大数相加算法

@Test
public void testBig() {
System.out.println(bigAdd("123456789", "9999999999999999999999999"));
}

public static String bigAdd(String a, String b) {
char[] charsA = new StringBuilder(a).reverse().toString().toCharArray();
char[] charsB = new StringBuilder(b).reverse().toString().toCharArray();

int maxLength = Math.max(charsA.length, charsB.length);

int[] result = new int[maxLength + 1];

int temp = 0;
for (int i = 0; i <= maxLength; i++) {
temp = result[i];

if (i < charsA.length) {
temp += charsA[i] - '0';
}

if (i < charsB.length) {
temp += charsB[i] - '0';
}

if (temp >= 10) {
temp -= 10;
result[i + 1] = 1;
}

result[i] = temp;

}

StringBuilder sb = new StringBuilder();
boolean flag = true;

for (int i = maxLength; i >= 0; i--) {
if (result[i] == 0 && flag) {
continue;
}

flag = false;
sb.append(result[i]);
}

return sb.toString();

}
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作者：懒惰的毛毛虫
来源：CSDN
原文：https://blog.csdn.net/u013278314/article/details/85171400
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