题解 | #高精度整数加法#

#import <Foundation/Foundation.h>

int main(int argc, char* argv[]) {
    NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

    char num1[10001];
    char num2[10001];

    gets(num1);
    gets(num2);

    NSString* str1 = [NSString stringWithFormat:@"%s", num1];
    NSString* str2 = [NSString stringWithFormat:@"%s", num2];

    // 默认str1更长 不够补0
    if (str1.length < str2.length) {
        NSString *temp = str1;
        str1 = str2;
        str2 = temp;
    }

    // 给str2前面补零
    NSInteger length = str1.length - str2.length;
    for (int i = 0; i < length; i++) {
        str2 = [NSString stringWithFormat:@"0%@", str2];
    }

    NSInteger tt = 0, tt1 = 0, tt2 = 0;
    NSString *st = @"";
    for (int i = str1.length - 1; i >= 0; i--) {
        tt1 = [[str1 substringWithRange:NSMakeRange(i, 1)] integerValue];
        tt2 = [[str2 substringWithRange:NSMakeRange(i, 1)] integerValue];
        st = [NSString stringWithFormat:@"%d%@", (tt1 + tt2 + tt)%10, st];
        tt = (tt1 + tt2 + tt) / 10;
    }
    if (tt > 0) {
        st = [NSString stringWithFormat:@"%d%@", tt, st];
    }
    printf("%@\n", st);


    // printf("%@-%@\n", str1, str2);
    // printf("str2 = %@", str2);

    [pool drain];
    return 0;
}