CF 722C Datastructure Hash

njzwj/Codeforces722C.cpp

@@ -0,0 +1,67 @@
+#include <bits/stdc++.h>
+using namespace std;
+const int N = 100010;
+typedef long long ll;
+int n, a[N], seq[N];
+struct Seg {
+    int l, r;
+    ll sum;
+    Seg() {}
+    Seg(int _l, int _r, ll _sum): l(_l), r(_r), sum(_sum) {}
+    bool operator<(const Seg &rhs) const {
+        return l<rhs.l;
+    }
+};
+int le[N], ri[N], tot, stk[N], tot2;
+Seg segs[N];
+set<ll> sums;
+ll ans[N];
+
+void ins(int x) {
+    int tar;
+    Seg ns;
+    ns=Seg(x, x, a[x]);
+    if (ri[x-1]>=0) {
+        tar=ri[x-1];
+        ns.l=segs[tar].l;
+        ns.sum+=segs[tar].sum;
+        sums.erase(segs[tar].sum);
+        stk[tot2++]=tar;
+    }
+    if (le[x+1]>=0) {
+        tar=le[x+1];
+        ns.r=segs[tar].r;
+        ns.sum+=segs[tar].sum;
+        sums.erase(segs[tar].sum);
+        stk[tot2++]=tar;
+    }
+    sums.insert(ns.sum);
+    if (tot2) {
+        tar=stk[--tot2];
+    }else tar=tot++;
+    segs[tar]=ns;
+    le[ns.l]=tar;
+    ri[ns.r]=tar;
+}
+
+int main() {
+    tot2=tot=0;
+    memset(le, 0xff, sizeof le);
+    memset(ri, 0xff, sizeof ri);
+    scanf("%d", &n);
+    for (int i=1;i<=n;++i) scanf("%d", a+i);
+    for (int i=0;i<n;++i) scanf("%d", seq+i);
+
+    ans[n-1]=0;
+    for (int i=n-1;i>0;--i) {
+        // INSERT
+        ins(seq[i]);
+        // CALCULATE
+        set<ll>::iterator it;
+        it=sums.end();
+        --it;
+        ans[i-1]=*it;
+    }
+    for (int i=0;i<n;++i) printf("%I64d\n", ans[i]);
+    return 0;
+}