[LeetCode101]Spiral Matrix2

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ]]

Analysis:

Similiar with the former one Spiral Matrix

Java

public int[][] generateMatrix(int n) {        int [][] result = new int[n][n];        int x1=0;        int y1=0;        int x2=n-1;        int y2 = n-1;        int val = 1;        while(x1<=x2 && y1<=y2){        for(int i=y1;i<=y2;i++)        result[x1][i] = val++;        for(int j = x1+1;j<=x2;j++)        result[j][y2] = val++;        if(x1!=x2)        for(int i=y2-1;i>=y1;i--)        result[x2][i] = val++;        if(y1!=y2)        for(int j=x2-1;j>y1;j--)        result[j][y1]=val++;        x1++;y1++;x2--;y2--;        }        return result;    }

c++

vector<vector<int> > generateMatrix(int n) {        vector<vector<int>> matrix(n);     if(n == 0) return matrix;     for(int i=0; i<n; i++){        matrix[i].resize(n);     }     int x1 = 0;     int y1 = 0;     int x2 = n - 1;     int y2 = n - 1;     int val = 1;     while(x1<=x2 && y1<=y2){        for(int j = y1; j<=y2; ++j)            matrix[x1][j] = val++;        for(int i = x1+1; i<=x2; ++i)            matrix[i][y2] = val++;        if(x2 !=x1)            for(int j = y2-1; j>=y1; --j)                matrix[x2][j] = val++;        if(y2 != y1)            for(int i = x2-1; i>x1; --i)                matrix[i][y1] = val++;        x1++, y1++, x2--, y2--;     }     return matrix;    }