[20251016] BOJ / P1 / 수열과 쿼리 23 / 권혁준

Author: oncsr

khj20006/202510/16 BOJ P1 수열과 쿼리 23.md

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+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+int N, Q, a[100000]{}, sq;
+ll fen[100001]{}, ans[100000]{};
+map<int, int> m;
+vector<tuple<int, int, int>> qs;
+
+void upt(int i, int v) {
+    for(;i<100001;i+=i&-i) fen[i] += v;
+}
+
+ll f(int i) {
+    ll ret = 0;
+    for(;i>0;i-=i&-i) ret += fen[i];
+    return ret;
+}
+
+int main(){
+    cin.tie(0)->sync_with_stdio(0);
+    
+    cin>>N>>Q;
+    sq = sqrt(N);
+    for(int i=0;i<N;i++) cin>>a[i], m[a[i]] = 0;
+    int c = 0;
+    for(auto &[x,y]:m) y = ++c;
+    for(int i=0;i<N;i++) a[i] = m[a[i]];
+
+    int t = 0;
+    qs.resize(Q);
+    for(auto &[a,b,x]:qs) cin>>a>>b, a--, b--, x = t++;
+    sort(qs.begin(), qs.end(), [](auto a, auto b) -> bool {
+        auto [al, ar, ax] = a;
+        auto [bl, br, bx] = b;
+        if(al/sq == bl/sq) return ar < br;
+        return al/sq < bl/sq;
+    });
+
+    int l = 0, r = -1;
+    ll res = 0;
+    for(auto [pl,pr,x]:qs) {
+        while(r < pr) {
+            res += f(c) - f(a[++r]);
+            upt(a[r],1);
+        }
+        while(pr < r) {
+            res -= f(c) - f(a[r]);
+            upt(a[r--],-1);
+        }
+        while(l < pl) {
+            res -= f(a[l]-1);
+            upt(a[l++],-1);
+        }
+        while(pl < l) {
+            res += f(a[--l]-1);
+            upt(a[l],1);
+        }
+        ans[x] = res;
+    }
+    for(int i=0;i<Q;i++) cout<<ans[i]<<'\n';
+
+}
+```