# Codeforces 519d A and B and interesting substrings (two-dimensional map + prefix and)

Source: Internet
Author: User

Question:
The string S is composed of only lowercase letters '~ 'Z' all gives a value. The substring T must be equal to the start and end characters of T, and the value of the intermediate character is 0,
The number of substrings T.
Solution:
Set a two-dimensional map such as Map <LL, int> MP [26] to record the occurrence times of the prefix and value ending with each letter.
Then calculate the prefix and sum. Calculate the ANS before calculating sum + val [s [I, because sum [I-1]-sum [x] = 0 can indicate sum (I-1 ~ X + 1) This section is 0.

Code

`1 # include <cstdio> 2 # include <iostream> 3 # include <algorithm> 4 # include <vector> 5 # include <string> 6 # include <string. h> 7 # include <cctype> 8 # include <math. h> 9 # include <stdlib. h> 10 # include <stack> 11 # include <queue> 12 # include <set> 13 # include <map> 14 # define LC (A) (a <1) 15 # define RC (A) (a <1 | 1) 16 # define mid (A, B) (a + B)> 1) 17 # define fin (name) freopen (name, "r", stdin) 18 # define fout (name) freopen (Na Me, "W", stdout) 19 # define CLR (ARR, Val) memset (ARR, Val, sizeof (ARR) 20 # DEFINE _ for (I, start, end) for (INT I = start; I <= end; I ++) 21 # define fast_io IOs: sync_with_stdio (false); cin. tie (0); 22 using namespace STD; 23 typedef long ll; 24 const int n = 1e5 + 5; 25 const ll inf64 = 1e18; 26 const int INF = 0x3f3f3f3f; 27 const double EPS = 1e-10; 28 29 int Val [30]; 30 Map <LL, int> MP [30]; 31 32 int main () {33 for (INT I = 0; I <26; I ++) {34 CIN> Val [I]; 35} 36 string STR; 37 CIN> STR; 38 ll sum = 0, ANS = 0; 39 For (INT I = 0; I <Str. length (); I ++) {40 int CH = STR [I]-'A'; 41 // calculate ans first, sum + = Val [CH] 42 // because sum [I-1]-sum [x] = 0 can indicate sum (I-1 ~ X + 1) This section is 0 43 ans + = MP [CH] [Sum]; 44 sum + = Val [CH]; 45 MP [CH] [Sum] ++; 46} 47 cout <ans <Endl; 48 return 0; 49}`

Codeforces 519d A and B and interesting substrings (two-dimensional map + prefix and)

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