'commit'

TangDou/JiShuanKe/2023-03-10/T3668_2.cpp

@@ -0,0 +1,69 @@
+#include <bits/stdc++.h>
+using namespace std;
+const int N = 2e5 + 10;
+
+int n, m;
+char S[N];
+vector<int> p[26];
+vector<int> f[26][26];
+int s[N][26];
+
+int lower_bound(vector<int> q, int l, int r, int x) {
+    while (l < r) {
+        int mid = (l + r) >> 1;
+        if (q[mid] >= x)
+            r = mid;
+        else
+            l = mid + 1;
+    }
+    return l;
+}
+int upper_bound(vector<int> q, int l, int r, int x) {
+    while (l < r) {
+        int mid = (l + r) >> 1;
+        if (q[mid] > x)
+            r = mid;
+        else
+            l = mid + 1;
+    }
+    return l;
+}
+
+// 使用手写版本的lower_bound,upper_bound
+int main() {
+    freopen("ridge.in", "r", stdin);
+    freopen("ridge.out", "w", stdout);
+
+    cin >> n >> m >> (S + 1);
+
+    for (int i = 1; i <= n; i++) {
+        int y = S[i] - 'a';
+        for (int x = 0; x < 26; x++) {
+            s[i][x] = s[i - 1][x];
+            f[x][y].push_back(s[i][x]);
+        }
+        p[y].push_back(i);
+        s[i][y]++;
+    }
+    for (int i = 0; i < 26; i++)
+        for (int j = 0; j < 26; j++)
+            for (int k = 1; k < (int)f[i][j].size(); k++)
+                f[i][j][k] += f[i][j][k - 1];
+
+    while (m--) {
+        int l, r;
+        string t;
+        cin >> l >> r >> t;
+
+        int x = t[0] - 'a', y = t[1] - 'a';
+        int ql = lower_bound(p[y], 0, (int)p[y].size(), l);
+        int qr = upper_bound(p[y], 0, (int)p[y].size(), r) - 1;
+        if (ql > qr) {
+            cout << 0 << endl;
+            continue;
+        }
+        int cnt = qr - ql + 1;
+        cout << f[x][y][qr] - (ql == 0 ? 0 : f[x][y][ql - 1]) - s[l - 1][x] * cnt << endl;
+    }
+    return 0;
+}