Codeforces 754A Lesha and array splitting (搜索)

题目链接 Lesha and array splitting

设s[i][j]为序列i到j的和，当s[i][j]≠0时，即可从i跳到j+1.目标为从1跳到n+1，所以按照题意暴力即可。

 #include <bits/stdc++.h>

 using namespace std;

 #define rep(i,a,b)              for(int i(a); i <= (b); ++i)
 #define dec(i,a,b)              for(int i(a); i >= (b); --i)

 const int Q     =            +       ;

 struct node{
     int x, y;
 } ans[Q];
 int s[Q][Q];
 int a[Q];

 bool flag = false;
 int n;
 int sum;

 void print(int x){
     printf("YES\n%d\n", x);
     rep(i, , x) printf("%d %d\n", ans[i].x, ans[i].y);
 }

 void dfs(int x, int step){

     if (flag) return;
     if (x == n + ){
         flag = true;
         print(step - );
         return;
     }

     dec(i, n, x) if (s[x][i]){
         ans[step].x = x, ans[step].y = i;
         dfs(i + , step + );
     }
 }    

 int main(){

     scanf("%d", &n);
     rep(i, , n) scanf("%d", a + i);
     rep(i, , n){
         sum = ;
         rep(j, i, n){
             sum += a[j];
             s[i][j] = sum;
         }
     }

     dfs(, );
     if (!flag) puts("NO");

     return ;

 }