ZOJ 1442 Dinner is the ready capacity repulsion principle + Java large number

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=442

Solving

X1 + x2 + x3 + .... + xn = m

where Xi belongs to [L, R]

The number of different solutions.

This problem needs to be used in large numbers, be careful.

The principle is the same as it did before. . The number of solutions for each XI greater than or equal to Li is calculated first. About this, how to solve, look at:

Http://www.cnblogs.com/liuweimingcprogram/p/6091396.html

Then let it go, enumeration has a number of damage conditions, is greater than R, minus, two, add back.

Because each r is different, it can only be violent Dfs. Which is the complexity of 2^n.

So complexity requires 2^n * constants.

Recommend a few questions.

Http://www.cnblogs.com/liuweimingcprogram/p/6134521.html

Http://www.cnblogs.com/liuweimingcprogram/p/6135008.html

The same way of thinking.

/** To change the license header, choose License Headers in the Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. *//** * * @authorLiu*/ImportJava.util.*; Importjava.math.*;//large number of header files Public classMain {Static Final intMAXN = 15; Static int[] be =New int[MAXN]; Static int[] en =New int[MAXN]; Static intN, M; StaticBigInteger ans;  Public Static voidMain (string[] args) {Scanner input=NewScanner (system.in); intt =Input.nextint ();  while((t--) > 0) {//The return value must be booln =Input.nextint (); M=Input.nextint (); intsum = 0;  for(inti = 1; I <= N; ++i) {Be[i]=Input.nextint (); En[i]=Input.nextint (); Sum+=Be[i]; } ans= Biginteger.zero;//Qing 0DFS (1, sum, 0);        System.out.println (ANS); }    }     Public StaticBigInteger C (intNintm) {//that's a big number .        if(N < m)returnBiginteger.zero; if(n = = m)returnBiginteger.one; BigInteger ans=Biginteger.one; intmx = Math.max (n-m, M);//Call Maximum Value        intMI = n-MX;  for(inti = 1; I <= mi; ++i) {ans= Ans.multiply (biginteger.valueof (mx + i));//methods for converting to large numbersAns = ans.divide (biginteger.valueof (i));//remember to receive the return value        }        returnans; }     Public Static voidDfsintCurintTotintHas ) {        if(cur = = n + 1) {            if(has% 2 = = 1) {ans= Ans.subtract (C (M-tot + n-1, n-1)); } ElseAns = Ans.add (C (M-tot + n-1, n-1)); return; } DFS (cur+ 1, Tot-be[cur] + en[cur] + 1, has + 1); DFS (cur+ 1, Tot, has); }}

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ZOJ 1442 Dinner is the ready capacity repulsion principle + Java large number