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| //字符串逆序
NSString *reverseStr(NSString *str){
NSMutableString *string=[[NSMutableString alloc] init];
for(int i=0;i<str.length;i++){
[string appendString:[str substringWithRange:NSMakeRange(str.length-1-i, 1)]];
}
return string;
}
//字符串分成数组
NSMutableArray *separateStringToArray(NSString *str){
NSMutableArray *marr = [NSMutableArray array];
for (NSInteger i = 0; i < str.length; i++) {
[marr addObject:[str substringWithRange:NSMakeRange(i, 1)]];
}
return marr;
}
NSString *findNextLargerNum(NSString *oriNum){
NSMutableString *finalStr = [NSMutableString string];
NSMutableArray *marr = separateStringToArray(oriNum);
for (NSInteger i = marr.count - 1; i > 0; i--) {
NSNumber *lastNum = [marr objectAtIndex:i];
NSNumber *preNum = [marr objectAtIndex:i-1];
if (lastNum.integerValue > preNum.integerValue) {
//截取字符串
NSString *rightStr = reverseStr([oriNum substringWithRange:NSMakeRange(i, oriNum.length - i)]);
NSString *leftStr = [oriNum substringWithRange:NSMakeRange(0,i)];
//第i-1位截取出来
NSString *leftCompareStr = [oriNum substringWithRange:NSMakeRange(i-1, 1)];
//和右边逐个对比
for (int j = 0; j < rightStr.length; j++) {
NSString *rightCompareStr = [rightStr substringWithRange:NSMakeRange(j, 1)];
if (leftCompareStr.integerValue < rightCompareStr.integerValue) {
NSMutableArray *finalArr = separateStringToArray([NSString stringWithFormat:@"%@%@",leftStr,rightStr]);
NSInteger leftIndex = [finalArr indexOfObject:leftCompareStr];
NSInteger rightIndex = [finalArr indexOfObject:rightCompareStr];
[finalArr exchangeObjectAtIndex:leftIndex withObjectAtIndex:rightIndex];
for (NSString *str in finalArr) {
[finalStr appendString:str];
}
break;
}
}
}
}
return finalStr.length?finalStr:oriNum;
}
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