牛客練習賽51 A B C

前字尾維護字串中b左邊a的個數和b的個數，對於每個b，它能構成的的abc的個數即為它前面a的個數乘以它後面c的個數

#include

using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
typedef pair<
int,
int> pii;
string s;
const
int maxn =
1e5+10;
ll a[maxn]
,c[maxn]
;int
main()
for(
int i = len -
1;i >=0;
-- i)
ll ans =0;
for(
int i =
1;i < len -1;
++ i)
if(s[i]
=='b'
) ans +
= a[i]
* c[i+1]
;    cout<'\n'
;return0;
}

#include

using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
typedef pair<
int,
int> pii;
string s1,s2;
int n,q;
const
int maxn =
1e5+10;
int pos[maxn][30
];intsolve()
return1;
}int
main()
while
(q --
)return0;
}

#include

using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
typedef pair<
int,
int> pii;
intmain()
}else
}return0;
}

牛客練習賽51

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牛客練習賽53 ABC

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題解 牛客練習賽51

字首a的數量，字尾c的數量，遇到b就計算一次答案。includeusing namespace std typedef long long ll const int n 1e5 100 char s n int cnt n int main int tmp 0 for int i 1 i n i p...