DigitCount-LCQ.cpp

/*
Check if Number Has Equal Digit Count and Digit Value

You are given a 0-indexed string num of length n consisting of digits.

Return true if for every index i in the range 0 <= i < n, the digit i occurs num[i] times in num, otherwise return false.

Example 1:

Input: num = "1210"
Output: true
Explanation:
num[0] = '1'. The digit 0 occurs once in num.
num[1] = '2'. The digit 1 occurs twice in num.
num[2] = '1'. The digit 2 occurs once in num.
num[3] = '0'. The digit 3 occurs zero times in num.
The condition holds true for every index in "1210", so return true.

Example 2:

Input: num = "030"
Output: false
Explanation:
num[0] = '0'. The digit 0 should occur zero times, but actually occurs twice in num.
num[1] = '3'. The digit 1 should occur three times, but actually occurs zero times in num.
num[2] = '0'. The digit 2 occurs zero times in num.
The indices 0 and 1 both violate the condition, so return false.
 

Constraints:

n == num.length
1 <= n <= 10
num consists of digits.
*/

class Solution {
public:
    bool digitCount(string num) {
        map<char,int>mp;
        for(int i=0;i<num.size();i++)   mp[num[i]-'0']++;
        for(int j=0;j<num.size();j++){
            int digit=num[j]-'0';
            if(mp[j]!=digit)    return false;
        }
        return true;
    }
};