# Next Closest Time in C++

Suppose we have a time represented in the format "HH: MM", we have to generate the next closest time by reusing the current digits. We can use the digit an unlimited number of times.

So, if the input is like "19:34", then the output will be "19:39" as the next closest time choosing from digits 1, 9, 3, 4, is 19:39. It is not 19:33, because this occurs 23 hours and 59 minutes later.

To solve this, we will follow these steps −

• Define a function eval(), this will take x,

• a := convert x[0] to string

• a := a + x[1]

• b := convert x[2] to string

• b := b + x[3]

• return a as integer * 60 + b as integer

• From the main method do the following −

• ret := blank string

• temp := blank string

• diff := inf

• Define an array time

• insert t[0] at the end of time

• insert t[1] at the end of time

• insert t[3] at the end of time

• insert t[4] at the end of time

• n := size of time

• src := blank string

• temp1 := blank string

• temp2 := blank string

• for initialize i := 0, when i < n, update (increase i by 1), do −

• src := src + time[i]

• for initialize i := 0, when i < n, update (increase i by 1), do −

• for initialize j := 0, when j < n, update (increase j by 1), do −

• for initialize k := 0, when k < n, update (increase k by 1), do −

• for initialize l := 0, when l < n, update (increase l by 1), do −

• temp1 := time[i]

• temp1 := temp1 + time[j]

• temp2 := time[k]

• temp2 := temp2 + time[l]

• if temp1 as number > 23 or temp2 as number > 59, then −

• temp := temp1 + temp2

• if temp is same as src, then −

• newDiff := eval(temp - eval(src))

• if newDiff < 0, then −

• newDiff := newDiff + (60 * 24)

• if newDiff < diff, then −

• diff := newDiff

• ret := temp1 + ":" + temp2

• return (if size of ret is same as 0, then t, otherwise ret)

## Example

Let us see the following implementation to get better understanding −

Live Demo

#include <bits/stdc++.h>
using namespace std;
class Solution {
public:
int eval(string x){
string a = to_string(x[0]);
a += x[1];
string b = to_string(x[2]);
b += x[3];
return stoi(a) * 60 + stoi(b);
}
string nextClosestTime(string t) {
string ret = "";
string temp = "";
int diff = INT_MAX;
vector<char> time;
time.push_back(t[0]);
time.push_back(t[1]);
time.push_back(t[3]);
time.push_back(t[4]);
int n = time.size();
string src = "";
string temp1 = "";
string temp2 = "";
for (int i = 0; i < n; i++)
src += time[i];
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
for (int k = 0; k < n; k++) {
for (int l = 0; l < n; l++) {
temp1 = time[i];
temp1 += time[j];
temp2 = time[k];
temp2 += time[l];
if (stoi(temp1) > 23 || stoi(temp2) > 59)
continue;
temp = temp1 + temp2;
if (temp == src)
continue;
int newDiff = eval(temp) - eval(src);
if (newDiff < 0)
newDiff += (60 * 24);
if (newDiff < diff) {
diff = newDiff;
ret = temp1 + ":" + temp2;
}
}
}
}
}
return ret.size() == 0 ? t : ret;
}
};
main(){
Solution ob;
cout<<(ob.nextClosestTime("19:34"));
}

## Input

"19:34"

## Output

19:39