January Cook Off 2018

CP/DecemberCookOff2017/prob2.py

@@ -0,0 +1,28 @@
+t=input()
+for i in range(t):
+    n=input()
+    arr=map(int,raw_input().split())
+    s=sum(arr)
+    if s%4!=0:
+        print -1
+    else:
+        a,b,c=[0,0,0]
+        for i in arr:
+            if i%4==1:
+                a+=1
+            elif i%4==2:
+                b+=1
+            elif i%4==3:
+                c+=1
+        #print a,b,c
+        #a,b,c=[2,5,8]
+        ans=0
+        ans+=min(a,c)
+        ans+=b/2
+        oth=max(a,c)-min(a,c)
+        #print a,b,c
+        if b%2==0:
+            ans+=3*(oth/4)
+        else:
+            ans+=2+3*((oth-2)/4)
+        print ans

CP/JanuaryCookOff2018/prob1.py

@@ -0,0 +1,15 @@
+import math
+for kohli in range(input()):
+    n,k,s = map(int,raw_input().split())
+    if(n<k or (6*n<7*k and s>=7)):
+        print("-1")
+        continue
+    c = int(math.ceil(s*1.0/(n*1.0/k*1.0)))
+    print(c)
+
+
+'''
+2
+16 2 10
+50 48 7
+'''

CP/JanuaryCookOff2018/prob2.py

@@ -0,0 +1,46 @@
+from __future__ import division
+from math import ceil
+from bisect import bisect_right as b_r
+from bisect import bisect_left as b_l
+for __ in range(int(input())):
+    a = map(int,raw_input().split())
+    s = (a[1]+a[2])%10
+    lis = [a[1],a[2]]
+    c=2
+    if(s%2==1):
+        lis.append(s)
+        c+=1
+        s = (s*2)%10
+    #print(s)
+    rem = (a[0]-c)%4
+    loop = (a[0]-c)//4
+    #print(rem,loop)
+    summ = sum(lis)
+    summ += (loop*20)%3
+    tt = [4,8,6,2,4,8,6,2]
+    st = '4862'
+    i = st.find(str(s))
+    for j in range(0,rem):
+        summ+=tt[i+j]
+    summ%=3
+    if(a[0]==2):
+        if((a[1]+a[2])%3==0):
+            print 'YES'
+        else:
+            print 'NO'
+    elif(s==0):
+        print 'NO'
+    elif(summ%3==0):
+        print 'YES'
+    else:
+        print 'NO'
+
+
+
+
+'''
+2
+5 3 4
+13 8 1
+
+'''

CP/JanuaryCookOff2018/prob3.cpp

@@ -0,0 +1,91 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int oo = 1000000000;
+
+const int N = 100005;
+
+int a[N], val[N][2], f[N][2], g[N][2];
+
+void solve() {
+    int n;
+    scanf("%d", &n);
+
+    for (int i = 1; i <= n; i++) {
+        scanf("%d", a+i);
+    }
+
+    if (n == 1) {
+        printf("0\n");
+        return;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        val[i][0] = a[i];
+        val[i][1] = a[n+1-i];
+    }
+
+    int m = n/2;
+    for (int i = 1; i <= m; i++)
+    for (int k = 0; k < 2; k++)
+        f[i][k] = g[i][k] = oo;
+    f[1][0] = g[1][0] = 0;
+    f[1][1] = g[1][1] = 1;
+    for (int i = 1; i < m; i++) {
+        for (int j = 0; j < 2; j++) {
+            for (int k = 0; k < 2; k++) {
+                int c1 = val[i][j];
+                int c2 = val[i+1][k];
+                if (((i & 1) && (c1 <= c2)) || (((i & 1) == 0) && c1 >= c2)) continue;
+                int t = n+1-i;
+                c1 = val[t][j];
+                c2 = val[t-1][k];
+                if (((t & 1) && (c1 <= c2)) || (((t & 1) == 0) && c1 >= c2)) continue;
+                f[i+1][k] = min(f[i+1][k], f[i][j] + k);
+            }
+            for (int k = 0; k < 2; k++) {
+                int c1 = val[i][j];
+                int c2 = val[i+1][k];
+                if (((i & 1) && (c1 >= c2)) || (((i & 1) == 0) && c1 <= c2)) continue;
+                int t = n+1-i;
+                c1 = val[t][j];
+                c2 = val[t-1][k];
+                if (((t & 1) && (c1 >= c2)) || (((t & 1) == 0) && c1 <= c2)) continue;
+                g[i+1][k] = min(g[i+1][k], g[i][j] + k);
+            }
+        }
+    }
+
+    int ans = oo;
+
+    if (n % 2 == 0) {
+        for (int j = 0; j < 2; j++) {
+            int c1 = val[m][j];
+            int c2 = val[m+1][j];
+            if (((m&1) && (c1 > c2)) || ((m&1) == 0 && (c1 < c2)))
+                ans = min(ans, f[m][j]);
+            if (((m&1) && (c1 < c2)) || ((m&1) == 0 && (c1 > c2)))
+                ans = min(ans, g[m][j]);
+        }
+    }
+    else {
+        int c1 = a[m];
+        int c2 = a[m+2];
+        int b = a[m+1];
+        if ((((m+1)&1) && b > c1 && b > c2) || (((m+1)&1) == 0 && b < c1 && b < c2))
+            ans = min(ans, min(f[m][0], f[m][1]));
+        if ((((m+1)&1) && b < c1 && b < c2) || (((m+1)&1) == 0 && b > c1 && b > c2))
+            ans = min(ans, min(g[m][0], g[m][1]));
+    }
+
+    if (ans >= oo) ans = -1;
+    printf("%d\n", ans);
+}
+
+int main() {
+    int ct;
+    scanf("%d", &ct);
+
+    while (ct--) solve();
+}