Ideas
Code
Python
if __name__ == '__main__':
s = input()
length = len(s)
dp = [[0] * length for _ in range(length)]
for i in range(length):
for j in range(length):
if i == j:
dp[i][j] = 1
elif i > j:
dp[i][j] = 0
else:
dp[i][j] = dp[i][j - 1] + (-1 if s[j] in s[i:j] else 1)
ans = 0
for line in dp:
ans += sum(line)
print(ans)
