Inversions

input/code.cpp: In function 'int main()':
input/code.cpp:16:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < s.length(); i++) {
                  ~~^~~~~~~~~~~~

#include <bits/stdc++.h>

#define ll long long
#define lll __int128
#define pii pair<int, int>
#define M 1000000007
#define N (1<<20)
using namespace std;

int main () {
	string s;
	cin>>s;
	int b;
	int w;
	b = w = 0;
	for (int i = 0; i < s.length(); i++) {
		int x = s[i] - '0';
		if (x != (i % 2)) b++;
		if (x != 1 - (i % 2)) w++;
	}
	cout<<min(b, w)<<endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED