Excellent Arrays Codeforces Solution

Excellent Arrays Codeforces Solution Let’s call an integer array a1,a2,…,ana1,a2,…,an good if ai≠iai≠i for each ii. Let F(a)F(a) be the number of pairs (i,j)(i,j) (1≤i<j≤n1≤i<j≤n) such that ai+aj=i+jai+aj=i+j. Let’s say that an array a1,a2,…,ana1,a2,…,an is excellent if: aa is good; l≤ai≤rl≤ai≤r for each ii; F(a)F(a) is the maximum possible among all good arrays of size nn. Given nn, ll and rr, calculate the number of excellent arrays modulo 109+7109+7.Input The first line contains a single integer tt (1≤t≤10001≤t≤1000) — the number of test cases. The first and only … Read more

Stringforces Codeforces Solution

Stringforces Codeforces Solution You are given a string ss of length nn. Each character is either one of the first kk lowercase Latin letters or a question mark. You are asked to replace every question mark with one of the first kk lowercase Latin letters in such a way that the following value is maximized. Let fifi be the maximum length substring of string ss, … Read more

Jumping Around Codeforces Solution

Jumping Around Codeforces Solution There is an infinite pond that can be represented with a number line. There are nn rocks in the pond, numbered from 11 to nn. The ii-th rock is located at an integer coordinate aiai. The coordinates of the rocks are pairwise distinct. The rocks are numbered in the increasing order of the coordinate, so a1<a2<⋯<ana1<a2<⋯<an. A robot frog … Read more

Manhattan Subarrays Codeforces Solution

Manhattan Subarrays Codeforces Solution Suppose you have two points p=(xp,yp)p=(xp,yp) and q=(xq,yq)q=(xq,yq). Let’s denote the Manhattan distance between them as d(p,q)=|xp−xq|+|yp−yq|d(p,q)=|xp−xq|+|yp−yq|. Let’s say that three points pp, qq, rr form a bad triple if d(p,r)=d(p,q)+d(q,r)d(p,r)=d(p,q)+d(q,r). Let’s say that an array b1,b2,…,bmb1,b2,…,bm is good if it is impossible to choose three distinct indices ii, jj, kk such that the points (bi,i)(bi,i), (bj,j)(bj,j) and (bk,k)(bk,k) form a bad triple. You are given an array a1,a2,…,ana1,a2,…,an. Calculate the number of good subarrays of aa. A subarray of the … Read more

Find The Array Codeforces Solution

Find The Array Codeforces Solution Let’s call an array aa consisting of nn positive (greater than 00) integers beautiful if the following condition is held for every ii from 11 to nn: either ai=1ai=1, or at least one of the numbers ai−1ai−1 and ai−2ai−2 exists in the array as well. For example: the array [5,3,1][5,3,1] is beautiful: for a1a1, the number a1−2=3a1−2=3 exists in the array; for a2a2, the number a2−2=1a2−2=1 exists in the array; for a3a3, the condition a3=1a3=1 holds; the array [1,2,2,2,2][1,2,2,2,2] is … Read more

Exciting Bets Codeforces Solution

Exciting Bets Solution Welcome to Rockport City! It is time for your first ever race in the game against Ronnie. To make the race interesting, you have bet aa dollars and Ronnie has bet bb dollars. But the fans seem to be disappointed. The excitement of the fans is given by gcd(a,b)gcd(a,b), where gcd(x,y)gcd(x,y) denotes the greatest common divisor (GCD) of integers xx and yy. To make … Read more

The Final Pursuit Codeforces Solution

The Final Pursuit Solution Finally, you have defeated Razor and now, you are the Most Wanted street racer. Sergeant Cross has sent the full police force after you in a deadly pursuit. Fortunately, you have found a hiding spot but you fear that Cross and his force will eventually find you. To increase your chances … Read more

RPD and Rap Sheet (Easy Version) Codeforces Solution

RPD and Rap Sheet (Easy Version) Solution This is the easy version of the problem. The only difference is that here k=2k=2. You can make hacks only if both the versions of the problem are solved. Every decimal number has a base kk equivalent. The individual digits of a base kk number are called kk-its. Let’s define the kk-itwise XOR of two kk-its aa and bb as (a+b)modk(a+b)modk. … Read more

Need for Pink Slips Codeforces Solution

Need for Pink Slips Solution After defeating a Blacklist Rival, you get a chance to draw 11 reward slip out of xx hidden valid slips. Initially, x=3x=3 and these hidden valid slips are Cash Slip, Impound Strike Release Marker and Pink Slip of Rival’s Car. Initially, the probability of drawing these in a random guess are cc, mm, and pp, respectively. See Also: Codeforces … Read more

Customising the Track Codeforces Solution

Customising the Track Solution Highway 201 is the most busy street in Rockport. Traffic cars cause a lot of hindrances to races, especially when there are a lot of them. The track which passes through this highway can be divided into nn sub-tracks. You are given an array aa where aiai represents the number of traffic cars in the ii-th sub-track. You … Read more

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