## C. Letters （前缀和、二分查找）

``` 1 #include <cstdio>
2 #include <string>
3 #include <iostream>
4 #include <algorithm>
5 #include <cstdbool>
6 #include <string.h>
7 #include <math.h>
8
9
10 using namespace std;
11
12 typedef long long LL;
13
14 LL a[2000005];
15 LL pre[2000005];
16
17 LL binarySearch(LL a[],LL n,LL key)
18 {
19     LL left = 1,right = n-1;
20     while (left <= right)
21     {
22         LL mid = (left + right) / 2;
23         if (a[mid] >= key)
24             right = mid - 1;
25         else if (a[mid] < key)
26             left = mid + 1;
27     }
28     return left;
29 }
30
31 int main()
32 {
33     ios_base::sync_with_stdio(0);
34     cin.tie(NULL);
35     LL n,m;
36     cin >> n >> m;
37     for (LL i=1;i<=n;i++)
38     {
39         cin >> a[i];
40         pre[i] = pre[i-1]+a[i];
41     }
42     LL temp;
43     for (LL i=1;i<=m;i++)
44     {
45         cin >> temp;
46         LL pos = binarySearch(pre,n,temp);
47         cout << pos << ' ' << temp-pre[pos-1] << endl;
48     }
49     return 0;
50 }```

``` 1 #include <cstdio>
2 #include <string>
3 #include <iostream>
4 #include <algorithm>
5 #include <cstdbool>
6 #include <string.h>
7 #include <math.h>
8
9
10 using namespace std;
11
12 typedef long long LL;
13
14 LL a[2000005];
15 LL pre[2000005];
16
17
18 int main()
19 {
20     ios_base::sync_with_stdio(0);
21     cin.tie(NULL);
22     LL n,m;
23     cin >> n >> m;
24     for (LL i=1;i<=n;i++)
25     {
26         cin >> a[i];
27         pre[i] = pre[i-1]+a[i];
28     }
29     LL temp;
30     for (LL i=1;i<=m;i++)
31     {
32         cin >> temp;
33         LL pos = lower_bound(pre+1,pre+1+n,temp)-pre;
34         cout << pos << ' ' << temp-pre[pos-1] << endl;
35     }
36     return 0;
37 }```