1128 N Queens Puzzle（20 分）
The "eight queens puzzle" is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other. Thus, a solution requires that no two queens share the same row, column, or diagonal. The eight queens puzzle is an example of the more general N queens problem of placing N non-attacking queens on an N×N chessboard. (From Wikipedia - "Eight queens puzzle".)
Here you are NOT asked to solve the puzzles. Instead, you are supposed to judge whether or not a given configuration of the chessboard is a solution. To simplify the representation of a chessboard, let us assume that no two queens will be placed in the same column. Then a configuration can be represented by a simple integer sequence (Q1,Q2,⋯,QN), where Qi is the row number of the queen in the i-th column. For example, Figure 1 can be represented by (4, 6, 8, 2, 7, 1, 3, 5) and it is indeed a solution to the 8 queens puzzle; while Figure 2 can be represented by (4, 6, 7, 2, 8, 1, 9, 5, 3) and is NOT a 9 queens' solution.
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 |
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|---|---|---|
| Figure 1 | Figure 2 |
Input Specification:
Each input file contains several test cases. The first line gives an integer K (1<K≤200). Then K lines follow, each gives a configuration in the format "N Q1 Q2 ... QN", where 4≤N≤1000 and it is guaranteed that 1≤Qi≤N for all i=1,⋯,N. The numbers are separated by spaces.
Output Specification:
For each configuration, if it is a solution to the N queens problem, print YES in a line; or NO if not.
Sample Input:
4
8 4 6 8 2 7 1 3 5
9 4 6 7 2 8 1 9 5 3
6 1 5 2 6 4 3
5 1 3 5 2 4
Sample Output:
YES
NO
NO
YES
解题思路：不能在同行同列和对角线出现，对角线就是abs(v[j]-v[i])==abs(j-i)，我一时只注意到相邻的，没有考虑到不相邻也可能是对角线，边输入边处理，不能同行就是行数相同。
#include<bits/stdc++.h>
using namespace std;
int main(void)
{
int T;
scanf("%d",&T);
while(T--)
{
int n,flag=1;
scanf("%d",&n);
vector<int>v(n);
for(int i=0;i<n;i++)
{
scanf("%d",&v[i]);
for(int j=0;j<i;j++)
{
if(v[i]==v[j]||(abs(v[j]-v[i])==abs(j-i)))
{
flag=0;
break;
}
}
}
printf("%s\n",flag==1?"YES":"NO");
}
return 0;
}